Geographic variation in sodium-glucose cotransporter 2 inhibitor and glucagon-like peptide-1 receptor agonist use in people with type 2 diabetes in New South Wales, Australia

AIM

Sodium-glucose cotransporter 2 inhibitors (SGLT2is) and glucagon-like peptide-1 receptor agonists (GLP-1RAs) improve glycaemic control and cardio-renal outcomes for people with type 2 diabetes (T2D). However, geographic and socio-economic variation in use is not well understood.

METHODS

We identified 367 829 New South Wales residents aged ≥40 years who dispensed metformin in 2020 as a proxy for T2D. We estimated the prevalence of use of other glucose-lowering medicines among people with T2D and the prevalence of SGLT2i and GLP-1RA use among people using concomitant T2D therapy (i.e. metformin + another glucose-lowering medicine). We measured the prevalence by small-level geography, stratified by age group, and characterized by remoteness and socio-economic status.

RESULTS

The prevalence of SGLT2i (29.7%) and GLP-1RA (8.3%) use in people with T2D aged 40-64 increased with geographic remoteness and in areas of greater socio-economic disadvantage, similar to other glucose-lowering medicines. The prevalence of SGLT2i (55.4%) and GLP-1RA (15.4%) among people using concomitant T2D therapy varied across geographic areas, with lower SGLT2i use in more disadvantaged areas and localized areas of high GLP-1RA use (2.5 times the median). Compared with people aged 40-64 years, the prevalence of SGLT2i and GLP-1RA use was lower in older age groups, but with similar patterns of variation across geographic areas.

CONCLUSIONS

The prevalence of SGLT2i and GLP-1RA use varied by geography, probably reflecting a combination of system- and prescriber-level factors. Socio-economic variation in GLP-1RA use was overshadowed by localized patterns of prescribing. Continued monitoring of variation can help shape interventions to optimize use among people who would benefit the most.

The Australian Health Care Homes trial: quality of care and patient outcomes. A propensity score-matched cohort study

OBJECTIVE

To assess the impact of the Health Care Homes (HCH) primary health care initiative on quality of care and patient outcomes.

DESIGN, SETTING

Quasi-experimental, matched cohort study; analysis of general practice data extracts and linked administrative data from ten Australian primary health networks, 1 October 2017 - 30 June 2021.

PARTICIPANTS

People with chronic health conditions (practice data extracts: 9811; linked administrative data: 10 682) enrolled in the HCH 1 October 2017 - 30 June 2019; comparison groups of patients receiving usual care (1:1 propensity score-matched).

INTERVENTION

Participants were involved in shared care planning, provided enhanced access to team care, and encouraged to seek chronic condition care at the HCH practice where they were enrolled. Participating practices received bundled payments based on clinical risk tier.

MAIN OUTCOME MEASURES

Access to care, processes of care, diabetes-related outcomes, hospital service use, risk of death.

RESULTS

During the first twelve months after enrolment, the mean numbers of general practitioner encounters (rate ratio, 1.14; 95% confidence interval [CI], 1.11-1.17) and Medicare Benefits Schedule claims for allied health services (rate ratio, 1.28; 95% CI, 1.24-1.33) were higher for the HCH than the usual care group. Annual influenza vaccinations (relative risk, 1.20; 95% CI, 1.17-1.22) and measurements of blood pressure (relative risk, 1.09; 95% CI, 1.08-1.11), blood lipids (relative risk, 1.19; 95% CI, 1.16-1.21), glycated haemoglobin (relative risk, 1.06; 95% CI, 1.03-1.08), and kidney function (relative risk, 1.13; 95% CI, 1.11-1.15) were more likely in the HCH than the usual care group during the twelve months after enrolment. Similar rate ratios and relative risks applied in the second year. The numbers of emergency department presentations (rate ratio, 1.09; 95% CI, 1.02-1.18) and emergency admissions (rate ratio, 1.13; 95% CI, 1.04-1.22) were higher for the HCH group during the first year; other differences in hospital use were not statistically significant. Differences in glycaemic and blood pressure control in people with diabetes in the second year were not statistically significant. By 30 June 2021, 689 people in the HCH group (6.5%) and 646 in the usual care group (6.1%) had died (hazard ratio, 1.07; 95% CI, 0.96-1.20).

CONCLUSIONS

The HCH program was associated with greater access to care and improved processes of care for people with chronic diseases, but not changes in diabetes-related outcomes, most measures of hospital use, or risk of death.

ution of the data and methods in real-world COVID-19 vaccine effectiveness studies on mortality: a oping eview protocol

BACKGROUND

Early evidence on COVID-19 vaccine efficacy came from randomised trials. Many important questions subsequently about vaccine effectiveness (VE) have been addressed using real-world studies (RWS) and have informed most vaccination policies globally. As the questions about VE have evolved during the pandemic so have data, study design, and analytical choices. This scoping review aims to characterise this evolution and provide insights for future pandemic planning-specifically, what kinds of questions are asked at different stages of a pandemic, and what data infrastructure and methods are used?

METHODS AND ANALYSIS

We will identify relevant studies in the Johns Hopkins Bloomberg School of Public Health VIEW-hub database, which curates both published and preprint VE RWS identified from PubMed, Embase, Scopus, Web of Science, the WHO COVID Database, MMWR, Eurosurveillance, medRxiv, bioRxiv, SSRN, Europe PMC, Research Square, Knowledge Hub, and Google. We will include RWS of COVID-19 VE that reported COVID-19-specific or all-cause mortality (coded as 'death' in the 'effectiveness studies' data set).Information on study characteristics; study context; data sources; design and analytic methods that address confounding will be extracted by single reviewer and checked for accuracy and discussed in a small group setting by methodological and analytic experts. A timeline mapping approach will be used to capture the evolution of this body of literature.By describing the evolution of RWS of VE through the COVID-19 pandemic, we will help identify options for VE studies and inform policy makers on the minimal data and analytic infrastructure needed to support rapid RWS of VE in future pandemics and of healthcare strategies more broadly.

ETHICS AND DISSEMINATION

As data is in the public domain, ethical approval is not required. Findings of this study will be disseminated through peer-reviewed publications, conference presentations, and working-papers to policy makers.

REGISTRATION

https://doi.org/10.17605/OSF.IO/ZHDKR.

Estimated Lifetime Cardiovascular, Kidney, and Mortality Benefits of Combination Treatment With SGLT2 Inhibitors, GLP-1 Receptor Agonists, and Nonsteroidal MRA Compared With Conventional Care in Patients With Type 2 Diabetes and Albuminuria

BACKGROUND

Sodium glucose cotransporter 2 inhibitors (SGLT2i), glucagon-like peptide-1 receptor agonists (GLP-1 RA), and the nonsteroidal mineralocorticoid receptor antagonist (ns-MRA) finerenone all individually reduce cardiovascular, kidney, and mortality outcomes in patients with type 2 diabetes and albuminuria. However, the lifetime benefits of combination therapy with these medicines are not known.

METHODS

We used data from 2 SGLT2i trials (CANVAS [Canagliflozin Cardiovascular Assessment] and CREDENCE [Canagliflozin and Renal Events in Diabetes with Established Nephropathy Clinical Evaluation]), 2 ns-MRA trials (FIDELIO-DKD [Finerenone in Reducing Kidney Failure and Disease Progression in Diabetic Kidney Disease] and FIGARO-DKD [Efficacy and Safety of Finerenone in Subjects With Type 2 Diabetes Mellitus and the Clinical Diagnosis of Diabetic Kidney Disease]), and 8 GLP-1 RA trials to estimate the relative effects of combination therapy versus conventional care (renin-angiotensin system blockade and traditional risk factor control) on cardiovascular, kidney, and mortality outcomes. Using actuarial methods, we then estimated absolute risk reductions with combination SGLT2i, GLP-1 RA, and ns-MRA in patients with type 2 diabetes and at least moderately increased albuminuria (urinary albumin:creatinine ratio ≥30 mg/g) by applying estimated combination treatment effects to participants receiving conventional care in CANVAS and CREDENCE.

RESULTS

Compared with conventional care, the combination of SGLT2i, GLP-1 RA, and ns-MRA was associated with a hazard ratio of 0.65 (95% CI, 0.55-0.76) for major adverse cardiovascular events (nonfatal myocardial infarction, nonfatal stroke, or cardiovascular death). The corresponding estimated absolute risk reduction over 3 years was 4.4% (95% CI, 3.0-5.7), with a number needed to treat of 23 (95% CI, 18-33). For a 50-year-old patient commencing combination therapy, estimated major adverse cardiovascular event-free survival was 21.1 years compared with 17.9 years for conventional care (3.2 years gained [95% CI, 2.1-4.3]). There were also projected gains in survival free from hospitalized heart failure (3.2 years [95% CI, 2.4-4.0]), chronic kidney disease progression (5.5 years [95% CI, 4.0-6.7]), cardiovascular death (2.2 years [95% CI, 1.2-3.0]), and all-cause death (2.4 years [95% CI, 1.4-3.4]). Attenuated but clinically relevant gains in event-free survival were observed in analyses assuming 50% additive effects of combination therapy, including for major adverse cardiovascular events (2.4 years [95% CI, 1.1-3.5]), chronic kidney disease progression (4.5 years [95% CI, 2.8-5.9]), and all-cause death (1.8 years [95% CI, 0.7-2.8]).

CONCLUSIONS

In patients with type 2 diabetes and at least moderately increased albuminuria, combination treatment of SGLT2i, GLP-1 RA, and ns-MRA has the potential to afford relevant gains in cardiovascular and kidney event-free and overall survival.

In-hospital outcomes by insurance type among patients undergoing percutaneous coronary interventions for acute myocardial infarction in New South Wales public hospitals

BACKGROUND

International evidence suggests patients receiving cardiac interventions experience differential outcomes by their insurance status. We investigated outcomes of in-hospital care according to insurance status among patients admitted in public hospitals with acute myocardial infarction (AMI) undergoing percutaneous coronary intervention (PCI).

METHODS

We conducted a cohort study within the Australian universal health care system with supplemental private insurance. Using linked hospital and mortality data, we included patients aged 18 + years admitted to New South Wales public hospitals with AMI and undergoing their first PCI from 2017-2020. We measured hospital-acquired complications (HACs), length of stay (LOS) and in-hospital mortality among propensity score-matched private and publicly funded patients. Matching was based on socio-demographic, clinical, admission and hospital-related factors.

RESULTS

Of 18,237 inpatients, 30.0% were privately funded. In the propensity-matched cohort (n = 10,630), private patients had lower rates of in-hospital mortality than public patients (odds ratio: 0.59, 95% CI: 0.45-0.77; approximately 11 deaths avoided per 1,000 people undergoing PCI procedures). Mortality differences were mostly driven by STEMI patients and those from major cities. There were no significant differences in rates of HACs or average LOS in private, compared to public, patients.

CONCLUSION

Our findings suggest patients undergoing PCI in Australian public hospitals with private health insurance experience lower in-hospital mortality compared with their publicly insured counterparts, but in-hospital complications are not related to patient health insurance status. Our findings are likely due to unmeasured confounding of broader patient selection, socioeconomic differences and pathways of care (e.g. access to emergency and ambulatory care; delays in treatment) that should be investigated to improve equity in health outcomes.

Long-term Mortality and Reintervention After Endovascular and Open Abdominal Aortic Aneurysm Repairs in Australia, Germany, and the United States

OBJECTIVE

To examine long-term outcomes after endovascular (EVAR) and open repairs (OAR) for intact abdominal aortic aneurysms in Australia, Germany, and the United States, using a unified study design.

BACKGROUND

Similarities and differences in long-term outcomes after EVAR versus OAR across countries remained unclear, given differences in designs across existing studies.

METHODS

We identified patients aged >65 years undergoing intact abdominal aortic aneurysm repairs during 2010-2017/2018. We compared long-term patient mortality and reintervention after EVAR and OAR using Kaplan-Meier analyses and Cox regressions. Propensity score matching was performed within each country to adjust for differences in baseline patient characteristics between procedure groups.

RESULTS

We included 3311, 4909, and 145363 patients from Australia, Germany, and the United States, respectively. The median patient age was 76 to 77 years, and most patients were males (77%-84%). Patient mortality was lower after EVAR than OAR within the first 60 days and became similar at 3-year follow-up (Australia 14.7% vs 16.5%, Germany 18.2% vs 19.7%, United States: 24.4% vs 24.4%). At the end of follow-up, patient mortality after EVAR was higher than OAR in Australia [ hazard ratio (HR) 95% CI: 1.21 (0.96-1.54)] but similar to OAR in Germany [HR 95% CI: 0.92 (0.80-1.07)] and the United States [HR 95% CI: 1.02 (0.99-1.05)]. The risk of reintervention after EVAR was more than twice that after OAR in Australia [HR 95% CI: 2.60 (1.09-6.15)], Germany [HR 95% CI: 4.79 (2.56-8.98)], and the United States [HR 95% CI: 2.67 (2.38-3.00)]. The difference in reintervention risk appeared early in German and United States patients.

CONCLUSIONS

This multinational study demonstrated important similarities in long-term outcomes after EVAR versus OAR across 3 countries. Variation in long-term mortality and reintervention comparisons indicates possible differences in patient profiles, surveillance, and best medical therapy across countries.

Comparison of long-term outcomes of bioprosthetic and mechanical aortic valve replacement in patients younger than 65 years

OBJECTIVES

The objectives of this study were to compare rates of mortality and reoperations for patients aged younger than 65 years who underwent surgical aortic valve replacement (AVR). AVR with a bioprosthetic valve (BV) is increasing among younger patients, however evidence to inform the choice between BV or mechanical valve is limited.

METHODS

We performed a retrospective cohort study using linked hospital and mortality data from Australia, for 3969 AVR patients between 2003 and 2018. We compared outcomes for valves in inverse probability of treatment-weighted cohorts, stratified according to age (18-54 years; 55-64 years). We used weighted Cox regression models to estimate hazard ratios (HRs) and weighted cumulative incidence function for subdistribution hazards, for follow-up intervals: 0 to 10 and >10 to 15 years.

RESULTS

Among patients aged 55 to 64 years, there was no difference in mortality at 0 to 10 years. However, at >10 to 15 years, mortality was higher among BV recipients (HR, 1.56; 95% CI, 1.01-2.42). There was no difference among patients aged 18 to 54 years. Reoperation rates for patients aged 55 to 64 years did not differ according to valve type at 0 to 10 years, but were higher for BV than mechanical valve at >10 to 15 years (HR, 2.87; 95% CI, 1.69-4.86). For patients aged 18 to 54 years, reoperation rates were consistently higher for BV at both time intervals (HR, 2.54 [95% CI, 1.03-6.25] and HR, 4.48 [95% CI, 2.15-9.32], respectively).

CONCLUSIONS

Patients aged 55 to 64 years who received a BV had a higher risk of mortality beyond 10 years. Rates of reoperations were higher among patients implanted with a BV in the entire cohort. Further investigation of long-term outcomes among patients with a BV is necessary. Continuous long-term monitoring of BV technologies will ensure evidence-based decision-making and regulation.

Trends in use of sodium-glucose co-transporter 2 inhibitors (SGLT2i) and glucagon-like peptide-1 receptor agonists (GLP-1RA) in Australia in the era of increased evidence of their cardiovascular benefits (2014-2022)

PURPOSE

To investigate trends in SGLT2i and GLP-1RA use in Australia in the era of increased evidence of their cardiovascular benefits.

METHODS

We used national dispensing claims for a 10% random sample of Australians to estimate the number of prevalent and new users (no dispensing in the prior year) of SGLT2i or GLP-1RA per month from January 2014 to July 2022. We assessed prescriber specialty and prior use of other antidiabetic and cardiovascular medicines as a proxy for evidence of type 2 diabetes (T2D) and cardiovascular conditions, respectively.

RESULTS

We found a large increase in the number of prevalent users (216-fold for SGLT2i; 11-fold for GLP-1RA); in July 2022 approximately 250,000 Australians were dispensed SGLT2i and 120,000 GLP-1RA. Most new users of SGLT2i or GLP-1RA had evidence of both T2D and cardiovascular conditions, although from 2022 onwards, approximately one in five new users of SGLT2i did not have T2D. The proportion of new users initiating SGLT2i by cardiologists increased after 2021, reaching 10.0% of initiations in July 2022. Among new users with evidence of cardiovascular conditions, empagliflozin was the most commonly prescribed SGLT2i, while dulaglutide or semaglutide was the most common GLP-1RA.

CONCLUSION

SGLT2i and GLP-1RA use is increasing in Australia, particularly in populations with higher cardiovascular risk. The increased use of SGLT2i among people without evidence of T2D suggests that best-evidence medicines are adopted in Australia across specialties, aligning with new evidence and expanding indications.

Persistence and Adherence to Cardiovascular Medicines in Australia

Background The burden of cardiovascular disease is increasing, with many people treated for multiple cardiovascular conditions. We examined persistence and adherence to medicines for cardiovascular disease treatment or prevention in Australia. Methods and Results Using national dispensing claims for a 10% random sample of people, we identified adults (≥18 years) initiating antihypertensives, statins, oral anticoagulants, or antiplatelets in 2018. We measured persistence to therapy using a 60-day permissible gap, and adherence using the proportion of days covered up to 3 years from initiation, and from first to last dispensing. We reported outcomes by age, sex, and cardiovascular multimedicine use. We identified 83 687 people initiating antihypertensives (n=37 941), statins (n=34 582), oral anticoagulants (n=15 435), or antiplatelets (n=7726). Around one-fifth of people discontinued therapy within 90 days, with 50% discontinuing within the first year. Although many people achieved high adherence (proportion of days covered ≥80%) within the first year, these rates were higher when measured from first to last dispensing (40.5% and 53.2% for statins; 55.6% and 80.5% for antiplatelets, respectively). Persistence was low at 3 years (17.5% antiplatelets to 37.3% anticoagulants). Persistence and adherence increased with age, with minor differences by sex. Over one-third of people had cardiovascular multimedicine use (reaching 92% among antiplatelet users): they had higher persistence and adherence than people using medicines from only 1 cardiovascular group. Conclusions Persistence to cardiovascular medicines decreases substantially following initiation, but adherence remains high while people are using therapy. Cardiovascular multimedicine use is common, and people using multiple cardiovascular medicines have higher rates of persistence and adherence.

Comparative effect of varenicline and nicotine patches on preventing repeat cardiovascular events

OBJECTIVE

To determine the comparative effectiveness of postdischarge use of varenicline versus prescription nicotine replacement therapy (NRT) patches for the prevention of recurrent cardiovascular events and mortality and whether this association differs by sex.

METHODS

Our cohort study used routinely collected hospital, pharmaceutical dispensing and mortality data for residents of New South Wales, Australia. We included patients hospitalised for a major cardiovascular event or procedure 2011-2017, who were dispensed varenicline or prescription NRT patches within 90day postdischarge. Exposure was defined using an approach analogous to intention to treat. Using inverse probability of treatment weighting with propensity scores to account for confounding, we estimated adjusted HRs for major cardiovascular events (MACEs), overall and by sex. We fitted an additional model with a sex-treatment interaction term to determine if treatment effects differed between males and females.

RESULTS

Our cohort of 844 varenicline users (72% male, 75% <65 years) and 2446 prescription NRT patch users (67% male, 65% <65 years) were followed for a median of 2.93 years and 2.34 years, respectively. After weighting, there was no difference in risk of MACE for varenicline relative to prescription NRT patches (aHR 0.99, 95% CI 0.82 to 1.19). We found no difference (interaction p=0.098) between males (aHR 0.92, 95% CI 0.73 to 1.16) and females (aHR 1.30, 95% CI 0.92 to 1.84), although the effect among females deviated from the null.

CONCLUSION

We found no difference between varenicline and prescription NRT patches in the risk of recurrent MACE. These results should be considered when determining the most appropriate choice of smoking cessation pharmacotherapy.

Long-Term Outcomes Following Elective Repair of Intact Abdominal Aortic Aneurysms: A Comparison Between Open Surgical and Endovascular Repair Using Linked Administrative and Clinical Registry Data

OBJECTIVE

Compare long-term mortality, secondary intervention and secondary rupture following elective endovascular aneurysm repair (EVAR) and open surgical repair (OSR).

BACKGROUND

EVAR has surpassed OSR as the most common procedure used to repair abdominal aortic aneurysm (AAA), but evidence regarding long-term outcomes is inconclusive.

METHODS

We included patients in linked clinical registry and administrative data undergoing EVAR or OSR for intact AAA between January 2010 and June 2019. We used an inverse probability of treatment-weighted survival analysis to compare all-cause mortality, cause-specific mortality, secondary interventions and secondary rupture, and evaluate the impact of secondary interventions and secondary rupture on all-cause mortality.

RESULTS

The study included 3460 EVAR and 427 OSR patients. Compared to OSR, the EVAR all-cause mortality rate was lower in the first 30 days [adjusted hazard ratio (HR) = 0.22, 95% confidence interval (CI) 0.140.33], but higher between 1 and 4 years (HR = 1.29, 95% CI 1.12-1.48) and after 4years (HR = 1.41, 95% CI 1.23-1.63). Secondary intervention rates were higher over the first 30 days (HR = 2.26, 95% CI 1.11-4.59), but lower between 1 and 4years (HR = 0.59, 95% CI 0.48-0.74). Secondary aortic intervention rates were higher across the entire follow-up period (HR = 2.52, 95% CI 2.06-3.07). Secondary rupture rates did not differ significantly (HR = 1.06, 95% CI 0.73-1.55). All-cause mortality beyond 1 year remained significantly higher for EVAR after adjusting for any secondary interventions, or secendary rupture.

CONCLUSIONS

EVAR has an early survival benefit compared to OSR. However, elevated long-term mortality and higher rates of secondary aortic interventions and subsequent aneurysm repair suggest that EVAR may be a less durable method of aortic aneurysm exclusion.

Editor's Choice - Comparison of Outcomes for Major Contemporary Endograft Devices Used for Endovascular Repair of Intact Abdominal Aortic Aneurysms

OBJECTIVE

To compare rates of mortality, rupture, and secondary intervention following endovascular repair (EVAR) of intact abdominal aortic aneurysms (AAA) using contemporary endograft devices from three major manufacturers.

METHODS

This was a retrospective cohort study using linked clinical registry (Australasian Vascular Audit) and all payer administrative data. Patients undergoing EVAR for intact AAA between 2010 and 2019 in New South Wales, Australia were identified. Rates of all cause death, secondary rupture, and secondary intervention (subsequent aneurysm repair; other secondary aortic intervention) were compared for patients treated with Cook, Medtronic, and Gore standard devices. Inverse probability of treatment weighted proportional hazards and competing risk regression were used to adjust for patient, clinical, and aneurysm characteristics, using Cook as the referent device.

RESULTS

This study identified 2 874 eligible EVAR patients, with a median follow up of 4.1 (maximum 9.5) years. Mortality rates were similar for patients receiving different devices (ranging between 7.0 and 7.3 per 100 person years). There was no statistically significant difference between devices in secondary rupture rates, which ranged between 0.4 and 0.5 per 100 person years. Patients receiving Medtronic and Gore devices tended to have higher crude rates of subsequent aneurysm repair (1.5 per 100 person years) than patients receiving Cook devices (0.8 per 100 person years). This finding remained in the adjusted analysis, but was only statistically significant for Medtronic devices (HR 1.57, 95% CI 1.02 - 2.47; HR 1.73, 95% CI 0.94 - 3.18, respectively).

CONCLUSION

Major endograft devices have similar overall long term safety profiles. However, there may be differences in rates of secondary intervention for some devices. This may reflect endograft durability, or patient selection for different devices based on aneurysm anatomy. Continuous comparative assessments are needed to guide evidence for treatment decisions across the range of available devices.

Trends and Outcomes for Percutaneous Coronary Intervention and Coronary Artery Bypass Graft Surgery in New South Wales from 2008 to 2019

Risk profiles are changing for patients who undergo percutaneous coronary intervention (PCI) and coronary artery bypass grafting (CABG). In Australia, little is known of the nature of these changes in contemporary practice and of the impact on patient outcomes. We identified all CABG (n = 40,805) and PCI (n = 142,399) procedures in patients aged ≥18 years in New South Wales, Australia, during 2008 to 2019. Between 2008 and 2019, the age- and gender-standardized revascularization rate increased by 20% (from 267/100,000 to 320/100,000 population) for all revascularizations. The increase in revascularization was particularly driven by a 35% increase (from 194/100,000 to 261/100,000) in PCI, whereas the rate of CABG decreased by 20% (from 73/100,000 to 59/100,000). Mean age and the prevalence of co-morbidities (especially diabetes and atrial fibrillation) increased for patients with PCI in more recent years but remained consistently lower than for patients with CABG. CABGs performed in patients presenting with a non-ST-segment-elevation acute coronary syndrome halved from 34.3% to 18.7% during the study period, whereas PCIs in this group decreased from 36.5% to 29.6%. Risk-adjusted in-hospital mortality decreased by 7.5 deaths/1,000 procedures per month for CABG but remained unchanged for PCI. Risk-adjusted readmission rates were consistently higher for CABG than for PCI and did not change significantly over time. In conclusion, we observed a dramatic shift over time from CABG to PCI as the revascularization procedure of choice, with the patient base for PCI extending to older and sicker patients. There was a large decrease in mortality after CABG, whereas mortality after PCI remained unchanged.

A nationwide study of multimedicine use in people treated with cardiovascular medicines in Australia

STUDY OBJECTIVE

Multimorbidity and multimedicine use are common in people with cardiovascular disease and can lead to harms, such as prescribing errors and drug interactions. We quantified multimedicine use in people treated with cardiovascular medicines in a national sample of Australians.

DESIGN

Cross-sectional study.

DATA SOURCE

Pharmaceutical dispensing claims for a 10% random sample of Australians.

PATIENTS

Australian adults dispensed any cardiovascular medicine between June and August 2019.

INTERVENTION

None.

MEASUREMENTS

We quantified the number and type of cardiovascular and non-cardiovascular medicines dispensed during the study period, and the number of unique prescribers, by age and sex.

MAIN RESULTS

We identified 493,081 people dispensed any cardiovascular medicine (median age = 67 years, 50.2% women). The population prevalence of cardiovascular medicine dispensing increased from 1.7% (n = 10,503) in people 18-34 years to 80.1% (n = 99,271) in people 75-84 years. Cardiovascular medicine dispensing varied by sex; women 18-34 years were more likely to be dispensed any cardiovascular medicine than men (male:female prevalence ratio [PR] = 0.84, 95% confidence interval [CI] = 0.81-0.87), whereas the prevalence of cardiovascular medicine dispensing was higher in men 35-44 years (PR = 1.27, 95% CI 1.24-1.30) and 45-54 years (PR = 1.24, 95% CI 1.22-1.26) and was similar between sexes in people ≥65 years. Overall, both women and men were dispensed a median of 2.0 (interquartile range [IQR] = 1.0-3.0) cardiovascular medicines. Two-thirds of people ≥65 years (73.5%; n = 208,524) were dispensed ≥2 cardiovascular medicines, with 16.6% (n = 6736) of people ≥85 years dispensed five or more. Women and men were dispensed a median of 2.0 (IQR = 1.0-5.0) and 2.0 (IQR = 0.0-4.0) non-cardiovascular medicines, respectively, to treat comorbid conditions, commonly gastroesophageal reflux disease medicines (32.2% of women and 26.6% of men), antibiotics (28.7% of women and 22.4% of men), and antidepressants (26.3% of women and 15.9% of men). One quarter of both sexes had multiple prescribers for their cardiovascular medicines alone, whereas 54.5% (n = 134,939) of women and 49.9% (n = 122,706) of men had multiple prescribers for all medicines.

CONCLUSION

Multimedicine use is common in people treated with cardiovascular medicines and presents a risk for inappropriate prescribing. Understanding the comorbid conditions commonly treated concurrently with cardiovascular disease can help improve co-prescribing guidelines and develop a person-centered approach to multimorbidity treatment.

Interaction effects of multimorbidity and frailty on adverse health outcomes in elderly hospitalised patients

We quantified the interaction of multimorbidity and frailty and their impact on adverse health outcomes in the hospital setting. Using aretrospective cohort study of persons aged ≥ 75 years, admitted to hospital during 2010–2012 in New South Wales, Australia, and linked with mortality data, we constructed multimorbidity, frailty risk and outcomes: prolonged length of stay (LOS), 30-day mortality and 30-day unplanned readmissions. Relative risks (RR) of outcomes were obtained using Poisson models with random intercept for hospital. Among 257,535 elderly inpatients, 33.6% had multimorbidity and elevated frailty risk, 14.7% had multimorbidity only, 19.9% had elevated frailty risk only and 31.8% had neither. Additive interactions were present for all outcomes, with a further multiplicative interaction for mortality and LOS. Mortality risk was 4.2 (95% CI 4.1–4.4), prolonged LOS 3.3 (95% CI 3.3–3.4) and readmission 1.8 (95% CI 1.7–1.9) times higher in patients with both factors present compared with patients with neither. In conclusion, multimorbidity and frailty coexist in older hospitalized patients and interact to increase the risk of adverse outcomes beyond the sum of their individual effects. Their joint effect should be considered in health outcomes research and when administering hospital resources.

Post-Discharge Antithrombotic Therapy Following Transcatheter Aortic Valve Implantation in Australian Patients

BACKGROUND

Guidelines recommend antithrombotic therapy for patients following transcatheter aortic valve implantation (TAVI) to reduce the risk of ischaemic events and bioprosthetic valve thrombosis.

OBJECTIVE

To describe antithrombotic dispensing within 30 days of discharge for Australian patients receiving TAVI.

METHODS

We performed a state-wide retrospective cohort study using linked hospital and medicines dispensing data from January 2013 to December 2018 for all patients receiving TAVI in New South Wales, Australia. We identified patients dispensed oral anticoagulants (vitamin K antagonists [warfarin], direct oral anticoagulants [DOACs]) or clopidogrel within 30 days of discharge. We examined demographic and clinical predictors of antithrombotic dispensing.

RESULTS

Our cohort comprised 1,217 patients who underwent TAVI; median age was 84 years and 707 (58.1%) were male. Of these, 808 patients (66.4%) had an antithrombotic dispensed within 30 days of hospital discharge. One-third (33.7%) of these patients were dispensed an anticoagulant (16.1% warfarin; 17.6% DOACs) and two-thirds (66.3%) were dispensed clopidogrel. Patients undergoing TAVI were more likely to be dispensed an antithrombotic medicine within 30-days of hospital discharge if they had been dispensed antithrombotic medicines (RR 1.07; 95% CI 1.03-1.11) or angiotensin-converting-enzyme inhibitors/angiotensin II receptor blockers (RR 1.04; 95% CI 1.00-1.07) in the 6 months prior to admission. Patients with a history of haemorrhage were less likely to be dispensed an antithrombotic medicine within 30 days of hospital discharge (RR 0.93; 95% CI 0.89-0.98).

CONCLUSIONS

We observed gaps in best evidence pharmacotherapy for patients post-TAVI, with almost one third of patients not receiving antithrombotic medicines post-discharge. Further research is needed to quantify the impact of emerging clinical guidelines recommending single antiplatelet therapy, on adherence to best-practice care.

An Observational Study of Clinical and Health System Factors Associated With Catheter Ablation and Early Ablation Treatment for Atrial Fibrillation in Australia

OBJECTIVE

To investigate clinical and health system factors associated with receiving catheter ablation (CA) and earlier ablation for non-valvular atrial fibrillation (AF).

METHODS

We used hospital administrative data linked with death registrations in New South Wales, Australia for patients with a primary diagnosis of AF between 2009 and 2017. Outcome measures included receipt of CA versus not receiving CA during follow-up (using Cox regression) and receipt of early ablation (using logistic regression).

RESULTS

Cardioversion during index admission (hazard ratio [HR] 1.96; 95% CI 1.75-2.19), year of index admission (HR 1.07; 1.07; 95% CI 1.05-1.10), private patient status (HR 2.65; 95% CI 2.35-2.97), and living in more advantaged areas (HR 1.18; 95% CI 1.13-1.22) were associated with a higher likelihood of receiving CA. A history of congestive heart failure, hypertension, diabetes, and myocardial infarction were associated with a lower likelihood of receiving CA. Private patient status (odds ratio [OR] 2.04; 95% CI 1.59-2.61), cardioversion during index admission (OR 1.25; 95% CI 1.0-1.57), and history of diabetes (OR 1.6; 95% CI 1.06-2.41) were associated with receiving early ablation.

CONCLUSIONS

Beyond clinical factors, private patients are more likely to receive CA and earlier ablation than their public counterparts. Whether the earlier access to ablation procedures in private patients is leading to differences in outcomes among patients with atrial fibrillation remains to be explored.

Rates of Low-Value Service in Australian Public Hospitals and the Association With Patient Insurance Status

IMPORTANCE

Low-value services have limited or no benefit to patients. Rates of low-value service in public hospitals may vary by patient insurance status, given that there may be different financial incentives for treatment of privately insured patients.

OBJECTIVE

To assess the variation in rates of 5 low-value services performed in Australian public hospitals according to patient funding status (ie, private or public).

DESIGN, SETTING, AND PARTICIPANTS

This retrospective cross-sectional study analyzed New South Wales public hospital data from January 2013 to June 2018. Patients included in the sample were over age 18 years and eligible to receive low-value services based on diagnoses and concomitant procedures. Data analysis was conducted from June to December 2020.

MAIN OUTCOMES AND MEASURES

Hospital-specific rates of low-value knee arthroscopic debridement, vertebroplasty for osteoporotic spinal fractures, hyperbaric oxygen therapy, oophorectomy with hysterectomy, and laparoscopic uterine nerve ablation for chronic pelvic pain were measured. For each measure, rates within each public hospital were compared by patient funding status descriptively and using multilevel models.

RESULTS

A total of 219 862 inpatients were included in analysis from 58 public hospitals across the 5 measures. A total of 38 365 (22 904 [59.7%] women; 12 448 [32.4%] aged 71-80 years) were eligible for knee arthroscopic debridement for osteoarthritis; 2520 (1924 [76.3%] women; 662 [26.3%] aged 71-80 years), vertebroplasty for osteoporotic spinal fractures; 162 285 (82 046 [50.6%] women; 28 255 [17.4%] aged 61-70 years), hyperbaric oxygen therapy; 15 916 (7126 [44.8%] aged 41-50 years), oophorectomy with hysterectomy; and 776 (327 [42.1%] aged 18-30 years), uterine nerve ablation for chronic pelvic pain. Overall rates of low-value services varied considerably between measures, with the lowest rate for hyperbaric oxygen therapy (0.3 procedures per 1000 inpatients [47 of 158 220 eligible inpatients]) and the highest for vertebroplasty (30.8 procedures per 1000 eligible patients [77 of 2501 eligible inpatients]). There was significant variation in rates between hospitals, with a few outlying hospitals (ie, <10), particularly for knee arthroscopy (range from 1.8 to 21.0 per 1000 eligible patients) and vertebroplasty (range from 13.1 to 70.4 per 1000 eligible patients), with higher numerical rates of low-value services among patients with private insurance than for those without. However, there was no association overall between patient insurance status and low-value services. Overall differences in rates among those with and without private insurance by individual procedure type were not statistically significant.

CONCLUSIONS AND RELEVANCE

There was significant variation in rates of low-value services in public hospitals. While there was no overall association between private insurance and rate of low-value services, private insurance may be associated with low-value service rates in some hospitals. Further exploration of factors specific to local hospitals and practices are needed to reduce this unnecessary care.

Medicine reviews: do they reduce benzodiazepine use in older Australians?

OBJECTIVES

Medicine reviews are an opportunity to identify and address inappropriate prescribing. The aim of this study was to explore changes in benzodiazepine use among older Australians following a medicine review.

STUDY TYPE

Retrospective observational cohort study using linked administrative data.

METHODS

We used Medicare Benefits Schedule and Pharmaceutical Benefits Scheme claims from a random 10% sample of Medicare beneficiaries. We identified people aged 65 years or older who received a medicine review in 2013-14 and were using benzodiazepines at the time of review. We identified a propensity score matched comparison cohort of those using benzodiazepines who did not receive a review. Two outcome measures were used: any benzodiazepine use and changes to the quantity of benzodiazepines dispensed (diazepam equivalents) from baseline to 90 and 180 days following a medicine review.

RESULTS

We identified 4002 people using benzodiazepines on the day of their medicine review, of whom approximately one-third discontinued benzodiazepines within 90 days (29.7%) and 180 days (36.4%;) after the review. We observed a similar discontinuation rate in the comparison group (32.6%, p = 0.006; and 38.0%, p = 0.12, respectively). In people who were dispensed lower quantities of benzodiazepines (less than 250 mg of diazepam equivalents in the 90 days before the medicine review), we found that 50.3% ceased using benzodiazepines or used lower quantities (measured as diazepam equivalents) following the medicine review (28.7% and 19.7% respectively). We also observed a reduction in the quantities used in people where initial exposure was high (3.4% ceased; 59.4% decreased). We observed a similar change in volume within the matched comparison group.

CONCLUSIONS

Medicine reviews are not associated with any additional reduction in benzodiazepine use among older adults, up to 180 days after review, beyond what was observed in the general population.

Patient and hospital factors associated with 30-day readmissions after coronary artery bypass graft (CABG) surgery: a systematic review and meta-analysis

BACKGROUND

Readmission after coronary artery bypass graft (CABG) surgery is associated with adverse outcomes and significant healthcare costs, and 30-day readmission rate is considered as a key indicator of the quality of care. This study aims to: quantify rates of readmission within 30 days of CABG surgery; explore the causes of readmissions; and investigate how patient- and hospital-level factors influence readmission.

METHODS

We conducted systematic searches (until June 2020) of PubMed and Embase databases to retrieve observational studies that investigated readmission after CABG. Random effect meta-analysis was used to estimate rates and predictors of 30-day post-CABG readmission.

RESULTS

In total, 53 studies meeting inclusion criteria were identified, including 8,937,457 CABG patients. The pooled 30-day readmission rate was 12.9% (95% CI: 11.3-14.4%). The most frequently reported underlying causes of 30-day readmissions were infection and sepsis (range: 6.9-28.6%), cardiac arrythmia (4.5-26.7%), congestive heart failure (5.8-15.7%), respiratory complications (1-20%) and pleural effusion (0.4-22.5%). Individual factors including age (OR per 10-year increase 1.12 [95% CI: 1.04-1.20]), female sex (OR 1.29 [1.25-1.34]), non-White race (OR 1.15 [1.10-1.21]), not having private insurance (OR 1.39 [1.27-1.51]) and various comorbidities were strongly associated with 30-day readmission rates, whereas associations with hospital factors including hospital CABG volume, surgeon CABG volume, hospital size, hospital quality and teaching status were inconsistent.

CONCLUSIONS

Nearly 1 in 8 CABG patients are readmitted within 30 days and the majority of these are readmitted for noncardiac causes. Readmission rates are strongly influenced by patients' demographic and clinical characteristics, but not by broadly defined hospital characteristics.

Evidence-practice gaps in P2Y12 inhibitor use after hospitalisation for acute myocardial infarction: findings from a new population-level data linkage in Australia

Background

P2Y₁₂ inhibitor therapy is recommended for 12 months in patients hospitalised for acute myocardial infarction (AMI) unless the bleeding risk is high.

Aims

To describe real‐world use of P2Y₁₂ inhibitor therapy following AMI hospitalisation.

Methods

We used population‐level linked hospital data to identify all patients discharged from a public hospital with a primary diagnosis of AMI between July 2011 and June 2013 in New South Wales and Victoria, Australia. We used dispensing claims to examine dispensing of a P2Y₁₂ inhibitor (clopidogrel, prasugrel or ticagrelor) within 30 days of discharge and multilevel models to identify predictors of post‐discharge dispensing and persistence of therapy to 1 year.

Results

We identified 31 848 patients hospitalised for AMI, of whom 56.8% were dispensed a P2Y₁₂ inhibitor within 30 days of discharge. The proportion of patients with post‐discharge dispensing varied between hospitals (interquartile range: 25.0–56.5%), and significant between‐hospital variation remained after adjusting for patient characteristics. Patient factors associated with the lowest likelihood of post‐discharge dispensing were: having undergone coronary artery bypass grafting (odds ratio (OR): 0.17; 95% confidence intervals (CI): 0.15–0.20); having oral anticoagulants dispensed 180 days before or 30 days after discharge (OR: 0.39, 95% CI: 0.35–0.44); major bleeding (OR: 0.68, 95% CI: 0.61–0.76); or being aged ≥85 years (OR: 0.68, 95% CI: 0.62–0.75). A total of 26.8% of patients who were dispensed a P2Y₁₂ inhibitor post‐discharge discontinued therapy within 1 year.

Conclusion

Post‐hospitalisation use of P2Y₁₂ inhibitor therapy in AMI patients is low and varies substantially by hospital of discharge. Our findings suggest strategies addressing both health system (hospital and physician) and patient factors are needed to close this evidence‐practice gap.

Long-term trajectories of medicine use among older adults experiencing polypharmacy in Australia

AIMS

To explore longitudinal changes in the number and type of medicines used among older people who experience polypharmacy.

METHODS

We used pharmaceutical claims for a 10% sample of Australian Pharmaceutical Benefits Scheme beneficiaries to identify people aged 70 years and older who were exposed to 5 or more medicines on 15 February 2014. Using group-based trajectory modelling, we explored changes in the quarterly number and type of medicines used over a 5-year period (2014-2018).

RESULTS

In our cohort of 98 539 people, we identified 2 predominant groups of medicine use: sustained polypharmacy (77% of people, 4 trajectories); and decreasing medicine use (23%, 3 trajectories). Within the sustained polypharmacy group, people in trajectories with a lower mean number of medicines (e.g. 6 unique medicines) had relatively stable trajectories, while those using a higher number of medicines (e.g. 15 unique medicines) experienced greater seasonal variation in the number and type of medicines used. On average, people continued to use 2/3 of their medicines (chemical substance level) across adjacent quarters. Within groups of decreasing medicine use, the most common trajectory was a slight drop in medicines within 3 months. Overall, 79% of people still experienced polypharmacy after 1 year.

CONCLUSION

Polypharmacy among older people is a sustained phenomenon, reflecting the chronic nature of multimorbidity within this population. However, there is an underlying volatility in the nature of medicines involved, reflecting both changes in treatment and seasonal fluctuation in dispensing. Ongoing prescribing vigilance is required, particularly for patients using very large amounts of medicines.

Antihypertensive polytherapy in Australia: prevalence of inappropriate combinations, 2013-2018

OBJECTIVES

To estimate the prevalence of inappropriate antihypertensive polytherapy in Australia.

METHODS

We used a nationally representative 10% sample of Pharmaceutical Benefits Scheme (PBS) eligible Australians and their dispensing history to identify people aged 18+ years exposed to at least one PBS-listed antihypertensive between 2012 and 2018. We measured prevalence of antihypertensive polypharmacy (≥40 days concomitant exposure), inappropriate antihypertensive combinations (against guideline recommendations; within-class polytherapy) and combinations to be used with caution.

RESULTS

Almost half (47.5%) of people using antihypertensives in 2018 experienced polytherapy. Among these, 2.4% had an inappropriate combination (1.5% against guidelines; 1.0% within-class polytherapy). Inappropriate combinations were more prevalent in people experiencing polytherapy with three (3.7%) or four (16.1%) antihypertensive medicines than people on dual therapy (0.7%). Inappropriate combinations occurred at a lower rate in people using fixed-dose rather than free-drug combinations for dual therapy (0 vs. 0.7%) and in those using three antihypertensives (2.4 vs. 7.3%); this was not the case for people using four or more antihypertensives (15.5 vs. 16.1%). Between 2013 and 2018, the prevalence of antihypertensive polytherapy was relatively stable (49-47%); however, the prevalence of inappropriate combinations among these patients halved (from 5.1 to 2.4%).

CONCLUSION

Antihypertensive polytherapy in Australia is common, but the prevalence of inappropriate combinations is low and decreasing over time, suggesting strong awareness of Australian clinical guidelines. However, in 2018, approximately 49 000 Australian adults experienced inappropriate polytherapy; prescribing of fixed-dose combinations in patients on dual or triple therapy may further reduce this inappropriate care, although increased vigilance treating patients with more than 3 antihypertensives is required.

Evidence-Practice Gaps in Postdischarge Initiation With Oral Anticoagulants in Patients With Atrial Fibrillation

Background

Oral anticoagulant (OAC) therapy reduces the risk of stroke in people with atrial fibrillation (AF), and is considered best practice; however, there is little Australian evidence around the uptake of OACs in this population.

Methods and Results

We used linked hospital admissions, pharmaceutical dispensing claims, medical services, and mortality data for people in Australia's 2 most populous states (July 2010 to June 2015). Among OAC‐naïve people hospitalized with AF, we estimated initiation of OAC therapy within 30 days of discharge, and persistence with therapy in the first year. We analyzed both outcomes using multivariable Cox regression. In 71 184 people with AF (median age 78 years, 49% female), 22.7% initiated OAC therapy. Initiation was lowest in July to December 2011 (17.0%) and highest in July to December 2014 (30.1%) after subsidy of the direct OACs. In adjusted analyses, initiation was most likely in people with a CHA₂DS₂‐VA score ≥7 (versus 0) (hazard ratio=6.25, 95% CI 5.08–7.69), and a history of venous thromboembolism (hazard ratio=2.65, 95% CI 2.49–2.83). Of the people who initiated OAC therapy, 39.9% discontinued within 1 year; a lower risk of discontinuation was associated with a CHA₂DS₂‐VA score ≥7 (versus 0) (hazard ratio=0.22, 95% CI 0.14–0.35), or initiation on a direct OAC (versus warfarin) (hazard ratio=0.55, 95% CI 0.50–0.60).

Conclusions

We found that OAC therapy was severely underutilized in people hospitalized with AF, even among high‐risk individuals. Reasons for this underuse, whether patient, prescriber, or hospital related, should be identified and addressed to reduce stroke‐related morbidity and mortality in people with AF.

Polypharmacy among older Australians, 2006-2017: a population-based study

OBJECTIVE

To estimate the prevalence of polypharmacy among Australians aged 70 years or more, 2006-2017.

DESIGN, SETTING AND PARTICIPANTS

Analysis of a random 10% sample of Pharmaceutical Benefits Scheme (PBS) data for people aged 70 or more who were dispensed PBS-listed medicines between 1 January 2006 and 31 December 2017.

MAIN OUTCOME MEASURES

Prevalence of continuous polypharmacy (five or more unique medicines dispensed during both 1 April - 30 June and 1 October - 31 December in a calendar year) among older Australians, and the estimated number of people affected in 2017; changes in prevalence of continuous polypharmacy among older concessional beneficiaries, 2006-2017.

RESULTS

In 2017, 36.1% of older Australians were affected by continuous polypharmacy, or an estimated 935 240 people. Rates of polypharmacy were higher among women than men (36.6% v 35.4%) and were highest among those aged 80-84 years (43.9%) or 85-89 years (46.0%). The prevalence of polypharmacy among PBS concessional beneficiaries aged 70 or more increased by 9% during 2006-2017 (from 33.2% to 36.2%), but the number of people affected increased by 52% (from 543 950 to 828 950).

CONCLUSIONS

The prevalence of polypharmacy among older Australians is relatively high, affecting almost one million older people, and the number is increasing as the population ages. Our estimates are probably low, as we could not take over-the-counter or complementary medicines or private prescriptions into account. Polypharmacy can be appropriate, but there is substantial evidence for its potential harm and the importance of rationalising unnecessary medicines, particularly in older people.

Do hospitals influence geographic variation in admission for preventable hospitalisation? A data linkage study in New South Wales, Australia

OBJECTIVE

Preventable hospitalisations are used internationally as a performance indicator for primary care, but the influence of other health system factors remains poorly understood. This study investigated between-hospital variation in rates of preventable hospitalisation.

SETTING

Linked health survey and hospital admissions data for a cohort study of 266 826 people aged over 45 years in the state of New South Wales, Australia.

METHOD

Between-hospital variation in preventable hospitalisation was quantified using cross-classified multiple-membership multilevel Poisson models, adjusted for personal sociodemographic, health and area-level contextual characteristics. Variation was also explored for two conditions unlikely to be influenced by discretionary admission practice: emergency admissions for acute myocardial infarction (AMI) and hip fracture.

RESULTS

We found significant between-hospital variation in adjusted rates of preventable hospitalisation, with hospitals varying on average 26% from the state mean. Patients served more by community and multipurpose facilities (smaller facilities primarily in rural areas) had higher rates of preventable hospitalisation. Community hospitals had the greatest between-hospital variation, and included the facilities with the highest rates of preventable hospitalisation. There was comparatively little between-hospital variation in rates of admission for AMI and hip fracture.

CONCLUSIONS

Geographic variation in preventable hospitalisation is determined in part by hospitals, reflecting different roles played by community and multipurpose facilities, compared with major and principal referral hospitals, within the community. Care should be taken when interpreting the indicator simply as a performance measure for primary care.

Reoperation after breast-conserving surgery for cancer in Australia: statewide cohort study of linked hospital data

OBJECTIVES

To investigate between-hospital variation in the probability of reoperation within 90 days of initial breast-conserving surgery (BCS), and the contribution of health system-level and other factors.

DESIGN

Population-based, retrospective cohort study.

SETTING

New South Wales (NSW), Australia.

PARTICIPANTS

Linked administrative hospitalisation data were used to define a cohort of adult women undergoing initial BCS for breast cancer in NSW between 1 July 2002 and 31 December 2013.

PRIMARY OUTCOME MEASURES

Multilevel, cross-classified models with patients clustered within hospitals and residential areas were used to examine factors associated with any reoperation, and either re-excision or mastectomy, within 90 days.

RESULTS

Of 34 458 women undergoing BCS, 29.1% underwent reoperation within 90 days, half of which were mastectomies. Overall, the probability of reoperation decreased slightly over time. However, there were divergent patterns by reoperation type; the probability of re-excision increased alongside a concomitant decrease in the probability of mastectomy. Significant between-hospital variation was observed. Non-metropolitan location and surgery at low-volume hospitals were associated with a higher overall probability of reoperation, and of mastectomy specifically, after accounting for patient-level factors, calendar year and area-level socioeconomic status. The magnitude of association with geographical location and surgical volume decreased over time.

CONCLUSIONS

Reoperation rates within 90 days of BCS varied significantly between hospitals. For women undergoing mastectomy after BCS, this represents a dramatic change in clinical course. Multilevel modelling suggests unwarranted clinical variation may be an issue, likely due to disparities in access to multidisciplinary breast cancer care and preoperative diagnostic procedures. However, the observed reduction in disparities over time is encouraging and indicates that guidelines and policy initiatives have the potential to improve regional breast cancer care.

Using Weighted Hospital Service Area Networks to Explore Variation in Preventable Hospitalization

Objective

To demonstrate the use of multiple‐membership multilevel models, which analytically structure patients in a weighted network of hospitals, for exploring between‐hospital variation in preventable hospitalizations.

Data Sources

Cohort of 267,014 people aged over 45 in NSW, Australia.

Study Design

Patterns of patient flow were used to create weighted hospital service area networks (weighted‐HSANs) to 79 large public hospitals of admission. Multiple‐membership multilevel models on rates of preventable hospitalization, modeling participants structured within weighted‐HSANs, were contrasted with models clustering on 72 hospital service areas (HSAs) that assigned participants to a discrete geographic region.

Data Collection/Extraction Methods

Linked survey and hospital admission data.

Principal Findings

Between‐hospital variation in rates of preventable hospitalization was more than two times greater when modeled using weighted‐HSANs rather than HSAs. Use of weighted‐HSANs permitted identification of small hospitals with particularly high rates of admission and influenced performance ranking of hospitals, particularly those with a broadly distributed patient base. There was no significant association with hospital bed occupancy.

Conclusion

Multiple‐membership multilevel models can analytically capture information lost on patient attribution when creating discrete health care catchments. Weighted‐HSANs have broad potential application in health services research and can be used across methods for creating patient catchments.

Visualising linked health data to explore health events around preventable hospitalisations in NSW Australia

OBJECTIVE

To explore patterns of health service use in the lead-up to, and following, admission for a 'preventable' hospitalisation.

SETTING

266 950 participants in the 45 and Up Study, New South Wales (NSW) Australia

METHODS

Linked data on hospital admissions, general practitioner (GP) visits and other health events were used to create visual representations of health service use. For each participant, health events were plotted against time, with different events juxtaposed using different markers and panels of data. Various visualisations were explored by patient characteristics, and compared with a cohort of non-admitted participants matched on sociodemographic and health characteristics. Health events were displayed over calendar year and in the 90 days surrounding first preventable hospitalisation.

RESULTS

The visualisations revealed patterns of clustering of GP consultations in the lead-up to, and following, preventable hospitalisation, with 14% of patients having a consultation on the day of admission and 27% in the prior week. There was a clustering of deaths and other hospitalisations following discharge, particularly for patients with a long length of stay, suggesting patients may have been in a state of health deterioration. Specialist consultations were primarily clustered during the period of hospitalisation. Rates of all health events were higher in patients admitted for a preventable hospitalisation than the matched non-admitted cohort.

CONCLUSIONS

We did not find evidence of limited use of primary care services in the lead-up to a preventable hospitalisation, rather people with preventable hospitalisations tended to have high levels of engagement with multiple elements of the healthcare system. As such, preventable hospitalisations might be better used as a tool for identifying sicker patients for managed care programmes. Visualising longitudinal health data was found to be a powerful strategy for uncovering patterns of health service use, and such visualisations have potential to be more widely adopted in health services research.

Relationship between use of general practice and healthcare costs at the end of life: a data linkage study in New South Wales, Australia

OBJECTIVE

This analysis investigated the relationships between healthcare expenditures in the last 6 months of life and use of general practitioner (GP) services in the preceding 12-month period among older residents of New South Wales, Australia.

METHODS

Questionnaire data (2006-2009) for more than 260,000 people aged 45 years and over were linked to individual hospital and death records and cost data. For 14,819 participants who died during follow-up, generalised linear mixed models were used to explore the relationships between costs of hospital, emergency department (ED) and Medicare-funded outpatient and pharmaceutical services in the last 6 months of life, and quintile of GP use in the 18-7 months before death. Analyses were adjusted for age at death, sex, educational level, language, private health insurance, household income, self-reported health status, functional limitation, psychological distress, number of comorbidities and geographic clustering.

RESULTS

Almost 85% of decedents had at least one hospitalisation in the last 6 months, and the mean (median) of total cost for each person in this period was $A20,453 (14,835). There was no significant difference in the hospital cost, including cost for preventable hospitalisations in the last 6 months of life, across quintiles of GP use in the 18-7 months before death. Participants in the lowest quintile of GP use incurred more ED costs, but ED costs were similar across the other quintiles of GP use. Costs for Medicare-funded outpatient services and pharmaceuticals increased steeply according to quintile of GP use.

CONCLUSIONS

In the Australian setting, there was no association between use of GP services in the 18-7 months before death and hospital costs in the last 6 months, but there was significant association with higher costs for outpatient services and pharmaceuticals. However, there was some indication that limited GP access might be associated with increased ED use at end of life.

Association of Continuity of Primary Care and Statin Adherence

Purpose

Deficiencies in medication adherence are a major barrier to effectiveness of chronic condition management. Continuity of primary care may promote adherence. We assessed the association of continuity of primary care with adherence to long-term medication as exemplified by statins.

Research Design

We linked data from a prospective study of 267,091 Australians aged 45 years and over to national data sets on prescription reimbursements, general practice claims, hospitalisations and deaths. For participants having a statin dispense within 90 days of study entry, we computed medication possession ratio (MPR) and usual provider continuity index (UPI) for the subsequent two years. We used multivariate Poisson regression to calculate the relative risk (RR) and 95% confidence interval (CI) for the association between tertiles of UPI and MPR adjusted for socio-demographic and health-related patient factors, including age, gender, remoteness of residence, smoking, alcohol intake, fruit and vegetable intake, physical activity, prior heart disease and speaking a language other than English at home. We performed a comparison approach using propensity score matching on a subset of the sample.

Results

36,144 participants were eligible and included in the analysis among whom 58% had UPI greater than 75%. UPI was significantly associated with 5% increased MPR for statin adherence (95% CI 1.04–1.06) for highest versus lowest tertile. Dichotomised analysis using a cut-off of UPI at 75% showed a similar effect size. The association between UPI and statin adherence was independent of socio-demographic and health-related factors. Stratification analyses further showed a stronger association among those who were new to statins (RR 1.33, 95% CI 1.15–1.54).

Conclusions

Greater continuity of care has a positive association with medication adherence for statins which is independent of socio-demographic and health-related factors.

Sociodemographic and health characteristics, rather than primary care supply, are major drivers of geographic variation in preventable hospitalizations in Australia

Supplemental Digital Content is available in the text.

Background:

Geographic rates of preventable hospitalization are used internationally as an indicator of accessibility and quality of primary care. Much research has correlated the indicator with the supply of primary care services, yet multiple other factors may influence these admissions.

Objective:

To quantify the relative contributions of the supply of general practitioners (GPs) and personal sociodemographic and health characteristics, to geographic variation in preventable hospitalization.

Methods:

Self-reported questionnaire data for 267,091 participants in the 45 and Up Study, Australia, were linked with administrative hospital data to identify preventable hospitalizations. Multilevel Poisson models, with participants clustered in their geographic area of residence, were used to explore factors that explain geographic variation in hospitalization.

Results:

GP supply, measured as full-time workload equivalents, was not a significant predictor of preventable hospitalization, and explained only a small amount (2.9%) of the geographic variation in hospitalization rates. Conversely, more than one-third (36.9%) of variation was driven by the sociodemographic composition, health, and behaviors of the population. These personal characteristics explained a greater amount of the variation for chronic conditions (37.5%) than acute (15.5%) or vaccine-preventable conditions (2.4%).

Conclusions:

Personal sociodemographic and health characteristics, rather than GP supply, are major drivers of preventable hospitalization. Their contribution varies according to condition, and if used for performance comparison purposes, geographic rates of preventable hospitalization should be reported according to individual condition or potential pathways for intervention.

Smoking and potentially preventable hospitalisation: the benefit of smoking cessation in older ages

AIMS

Reducing preventable hospitalisation is a priority for health systems worldwide. This study sought to quantify the contribution of smoking to preventable hospitalisation in older adults and the potential benefits of smoking cessation.

METHODS

Self-reported smoking data for 267,010 Australian men and women aged 45+ years linked with administrative hospital data were analysed using Cox's models to estimate the effects on risk of hospitalisation for congestive heart failure (CHF), diabetes complications, chronic obstructive pulmonary disease (COPD) and angina. The impacts of smoking and quitting smoking were also quantified using risk advancement periods (RAP).

RESULTS

The cohort included 7% current smokers, 36% former smokers and 57% never smokers. During an average follow-up of 2.7 years, 4% of participants had at least one hospitalisation for any of the study conditions (0.8% for CHF, 1.7% for diabetes complications, 0.8% for COPD and 1.4% for angina). Compared to never smokers, the adjusted hazard ratio for hospitalisation for any of the conditions for current smokers was 1.89 (95% CI 1.75-2.03), and the RAP was 3.8 years. There were strong dose-response relationships between smoking duration, smoking intensity and cumulative smoking dose on hospitalisation risk. The excess risk of hospitalisation and RAP for COPD was reduced within 5 years of smoking cessation across all age groups, but risk reduction for other conditions was only observed after 15 years.

CONCLUSION

Smoking is associated with increased risk of preventable hospitalisation for chronic conditions in older adults and smoking cessation, even at older ages, reduces this risk.

Minimal excess risk of cancer and reduced risk of death from cancer in Australian Department of Veterans' Affairs clients: a record linkage study

OBJECTIVE

To quantify the risk of incident cancer and cancer-related mortality in Australian Government Department of Veterans' Affairs (DVA) clients.

METHODS

A population-based record linkage study of 75,482 adult clients residing in New South Wales (NSW) from 2000 to 2007; median age 75 years (interquartile range, 68-79); 57% male. Standardised incidence ratios (SIRs) and mortality ratios (SMRs) for any cancer and by cancer type were calculated, relative to the NSW population.

RESULTS

The risk of any cancer was slightly increased for males (SIR 1.07, 95%CI 1.04-1.10) but not females (SIR 1.00, 95%CI 0.96-1.04). Males exhibited a significantly elevated risk of prostate cancer (SIR 1.08), cutaneous melanoma (SIR 1.19), head and neck cancer (SIR 1.27) and connective tissue cancer (SIR 1.52). Females did not exhibit excess risk for any cancer type. Risk of cancer death was significantly reduced for any cancer (male SMR 0.78, 95%CI 0.75-0.81; female SMR 0.80, 95%CI 0.76-0.85) and for a range of haematopoietic and solid neoplasms including prostate (SMR 0.57), breast (SMR 0.62) and colon cancer (male SMR 0.67; female SMR 0.71).

CONCLUSION

Cancer incidence rates are largely similar, and mortality rates moderately lower, for DVA clients compared to the NSW general population.

IMPLICATIONS

These risk patterns may reflect service-related history, a healthy-survivor effect, competing risk of death, and/or comprehensive health care entitlements with minimal to no co-payments. Our findings suggest DVA clients are probably accessing cancer screening services. Outcomes after cancer diagnosis are good, most probably due to comprehensive health care entitlements.

The contribution of geography to disparities in preventable hospitalisations between indigenous and non-indigenous Australians

OBJECTIVES

To quantify the independent roles of geography and Indigenous status in explaining disparities in Potentially Preventable Hospital (PPH) admissions between Indigenous and non-Indigenous Australians.

DESIGN, SETTING AND PARTICIPANTS

Analysis of linked hospital admission data for New South Wales (NSW), Australia, for the period July 1 2003 to June 30 2008.

MAIN OUTCOME MEASURES

Age-standardised admission rates, and rate ratios adjusted for age, sex and Statistical Local Area (SLA) of residence using multilevel models.

RESULTS

PPH diagnoses accounted for 987,604 admissions in NSW over the study period, of which 3.7% were for Indigenous people. The age-standardised PPH admission rate was 76.5 and 27.3 per 1,000 for Indigenous and non-Indigenous people respectively. PPH admission rates in Indigenous people were 2.16 times higher than in non-Indigenous people of the same age group and sex who lived in the same SLA. The largest disparities in PPH admission rates were seen for diabetes complications, chronic obstructive pulmonary disease and rheumatic heart disease. Both rates of PPH admission in Indigenous people, and the disparity in rates between Indigenous than non-Indigenous people, varied significantly by SLA, with greater disparities seen in regional and remote areas than in major cities.

CONCLUSIONS

Higher rates of PPH admission among Indigenous people are not simply a function of their greater likelihood of living in rural and remote areas. The very considerable geographic variation in the disparity in rates of PPH admission between Indigenous and non-Indigenous people indicates that there is potential to reduce unwarranted variation by characterising outlying areas which contribute the most to this disparity.

Factors influencing adherence in long-term use of statins

PURPOSE

To assess the factors influencing adherence in long-term medication use as exemplified by statins.

METHODS

Data from an in-depth survey of Australians aged 45 years and over were linked to national prescription reimbursement data to assess medication possession ratio (MPR) for statins for the middle two years of a four-year period of statin possession. Poisson regression was used to calculate the relative risk (RR) for adherence (MPR ≥ 80%) for patient characteristics and factors related to access to and need for health care services. Separate models were fit for patients receiving healthcare concession subsidies and those who do not ('general beneficiaries').

RESULTS

In the analysis, 42 492 concessional and 16 110 general beneficiary patients were included, with 80.1% and 56.7% showing MPR ≥ 80%, respectively. In both models, RR for adherence was significantly elevated for older (age 65+) and less healthy (worse self-rated health, pre-existing heart condition or obese) individuals, and for those who had private health insurance. Significantly lower RR (i.e. more non-adherence) was found for individuals reporting speaking a language other than English at home, who were smokers, were employed, and had higher levels of education, and for those who reported psychological distress. Income had no significant relationship with adherence, and the pattern of adherence by remoteness of area of residence was inconsistent.

CONCLUSIONS

Poor adherence in long-term use of statins is commonplace, but a number of key predictors-including age, language other than English spoken at home, smoking status and psychological distress-are readily assessable by the prescribing practice.

Disentangling the impacts of geography and Aboriginality on serious road transport injuries in New South Wales

Aboriginal people in Australia have higher rates of transport injury than non-Aboriginal people, but a greater proportion of Aboriginal people live in rural or remote areas where risk of these injuries is higher. This paper investigated the contributing effect of geography on the relationship between Aboriginality and road transport injury rates in the state of New South Wales. Linked hospital admission and mortality records for individuals for the years 2001-2007 were grouped into distinct injury events. Multilevel Poisson regression was used to examine disparities in injury rates between Aboriginal and non-Aboriginal people clustered within geographic areas of residence. Overall, Aboriginal people had higher rates of road transport injuries (IRR: 1.18, 95% CIs: 1.09-1.28). However, there was no significant difference when geographic clustering was taken into account (IRR: 1.00, 95% CIs: 0.96-1.04). This effect was further influenced by mode of transport for the injury, with Aboriginal people having higher rates of pedestrian (IRR: 1.96, 95% CIs: 1.75-2.19) and lower rates of motorcycle (IRR: 0.64, 95% CIs: 0.59-0.70) injuries in all almost all local areas, while there was no systematic pattern across geographic areas for small vehicle injuries (IRR: 1.01, 95% CIs: 0.94-1.08). Geography plays an important role in the population disparity of road transport injuries between Aboriginal and non-Aboriginal people, and has a differential impact for different types of road transport injury. Exploring how individual and geographic factors influence patterns of disparity allows for clearer targeting of future intervention strategies.

Latitude gradients for lymphoid neoplasm subtypes in Australia support an association with ultraviolet radiation exposure

Given the uncertainty surrounding solar ultraviolet radiation (UVR) exposure and risk of lymphoid neoplasms, we performed an ecological analysis of national Australian data for incident cases diagnosed between 2002 and 2006. Subtype-specific incidence was examined by latitude band (<29°S, 29-36°S, ≥37°S), a proxy for ambient UVR exposure, using multiple Poisson regression, adjusted for sex, age-group and calendar year. Incidence increased with distance from the equator for several mature B-cell non-Hodgkin lymphomas, including diffuse large B-cell [incidence rate ratio (IRR) = 1.37; 95% confidence interval (CI): 1.16-1.61 for latitude ≥37°S relative to <29°S], lymphoplasmacytic (IRR = 1.34; 95% CI: 1.12-1.61), mucosa-associated lymphoid tissue (IRR = 1.32; 95% CI: 0.97-1.80) and mantle cell lymphoma (IRR = 1.29; 95% CI: 1.05-1.58), as well as plasmacytoma (IRR = 1.52; 95% CI: 1.09-2.11) and plasma cell myeloma (IRR = 1.15; 95% CI: 1.03-1.27). A similar pattern was observed for several mature cutaneous T-cell neoplasms, including primary cutaneous anaplastic large cell lymphoma (IRR = 4.26; 95% CI: 1.85-9.84), mycosis fungoides/Sézary syndrome (IRR = 1.72; 95% CI: 1.20-2.46), and peripheral T-cell lymphoma not otherwise specified (NOS) (IRR = 1.53; 95% CI: 1.17-2.00). Incidence of mixed cellularity/lymphocyte-depleted (IRR = 1.60; 95% CI: 1.16-2.20) and nodular sclerosis Hodgkin lymphoma (IRR = 1.57; 95% CI: 1.33-1.85) also increased with distance from the equator. Many of these subtypes have a known association with infection or immune dysregulation. Our findings support a possible protective effect of UVR exposure on the risk of several lymphoid neoplasms, possibly through vitamin D-related immune modulation critical in lymphomagenesis.

Trends in planned early birth: a population-based study

OBJECTIVE

The purpose of this study was to describe trends and outcomes of planned births.

STUDY DESIGN

Data from linked birth and hospital records for 779,521 singleton births at ≥33 weeks' gestation from 2001-2009 were used to determine trends in planned births (prelabor cesarean section and labor inductions). Adverse outcomes were composite indicators of maternal and neonatal morbidity/death.

RESULTS

From 2001-2009, there were increases in labor inductions and prelabor cesarean deliveries at <40 weeks' gestation, but no decrease in the stillbirth rate (trend P = .34). By 2009, 14.9% of live births at ≥33 weeks' gestation were prelabor cesarean deliveries before the due date; 11.4% were inductions. As planned births increased, maternal risks shifted, which included a decline in inductions with maternal hypertension from 31.9-23.9%. Earlier birth was contemporaneous with increases (trend P < .001) in neonatal and maternal morbidity rates from 3.0-3.2% and 1.1-1.5%, respectively.

CONCLUSION

Planned birth before the due date is increasing without a contemporaneous reduction of stillbirths.

Self-reported history of infections and the risk of non-Hodgkin lymphoma: an InterLymph pooled analysis

We performed a pooled analysis of data on self-reported history of infections in relation to the risk of non-Hodgkin lymphoma (NHL) from 17 case-control studies that included 12,585 cases and 15,416 controls aged 16-96 years at recruitment. Pooled odds ratios (OR) and 95% confidence intervals (95% CI) were estimated in two-stage random-effect or joint fixed-effect models, adjusting for age, sex and study centre. Data from the 2 years before diagnosis (or date of interview for controls) were excluded. A self-reported history of infectious mononucleosis was associated with an excess risk of NHL (OR = 1.26, 95% CI = 1.01-1.57 based on data from 16 studies); study-specific results indicate significant (I(2) = 51%, p = 0.01) heterogeneity. A self-reported history of measles or whooping cough was associated with an approximate 15% reduction in risk. History of other infection was not associated with NHL. We find little clear evidence of an association between NHL risk and infection although the limitations of data based on self-reported medical history (particularly of childhood illness reported by older people) are well recognized.

Development of a maternity hospital classification for use in perinatal research

We aimed to develop a maternity hospital classification, using stable and easily available criteria, that would have wide application in maternity services research and allow comparison across state, national and international jurisdictions. A classification with 13 obstetric groupings (12 hospital groups and home births) was based on neonatal care capability, urban and rural location, annual average number of births and public/private hospital status. In a case study of early elective birth we demonstrate that neonatal morbidity differs according to the maternity hospital classification, and also that the 13 groups can be collapsed in ways that are pragmatic from a clinical and policy decision-making perspective, and are manageable for analysis.

Birth order and risk of non-hodgkin lymphoma--true association or bias?

There is inconsistent evidence that increasing birth order may be associated with risk of non-Hodgkin lymphoma (NHL). The authors examined the association between birth order and related variables and NHL risk in a pooled analysis (1983-2005) of 13,535 cases and 16,427 controls from 18 case-control studies within the International Lymphoma Epidemiology Consortium (InterLymph). Overall, the authors found no significant association between increasing birth order and risk of NHL (P-trend = 0.082) and significant heterogeneity. However, a significant association was present for a number of B- and T-cell NHL subtypes. There was considerable variation in the study-specific risks which was partly explained by study design and participant characteristics. In particular, a significant positive association was present in population-based studies, which had lower response rates in cases and controls, but not in hospital-based studies. A significant positive association was present in higher-socioeconomic-status (SES) participants only. Results were very similar for the related variable of sibship size. The known correlation of high birth order with low SES suggests that selection bias related to SES may be responsible for the association between birth order and NHL.

Atopic disease and risk of non-Hodgkin lymphoma: an InterLymph pooled analysis

We performed a pooled analysis of data on atopic disease and risk of non-Hodgkin lymphoma (NHL) from 13 case-control studies, including 13,535 NHL cases and 16,388 controls. Self-reported atopic diseases diagnosed 2 years or more before NHL diagnosis (cases) or interview (controls) were analyzed. Pooled odds ratios (OR) and 95% confidence intervals (95% CI) were computed in two-stage random-effects or joint fixed-effects models, and adjusted for age, sex, and study center. When modeled individually, lifetime history of asthma, hay fever, specific allergy (excluding hay fever, asthma, and eczema), and food allergy were associated with a significant reduction in NHL risk, and there was no association for eczema. When each atopic condition was included in the same model, reduced NHL risk was only associated with a history of allergy (OR, 0.80; 95% CI, 0.68-0.94) and reduced B-cell NHL risk was associated with history of hay fever (OR, 0.85; 95% CI, 0.77-0.95) and allergy (OR, 0.84; 95% CI, 0.76-0.93). Significant reductions in B-cell NHL risk were also observed in individuals who were likely to be truly or highly atopic-those with hay fever, allergy, or asthma and at least one other atopic condition over their lifetime. The inverse associations were consistent for the diffuse large B-cell and follicular subtypes. Eczema was positively associated with lymphomas of the skin; misdiagnosis of lymphoma as eczema is likely, but progression of eczema to cutaneous lymphoma cannot be excluded. This pooled study shows evidence of a modest but consistent reduction in the risk of B-cell NHL associated with atopy.

Incidence of cancers in people with HIV/AIDS compared with immunosuppressed transplant recipients: a meta-analysis

BACKGROUND

Only a few types of cancer are recognised as being directly related to immune deficiency in people with HIV/AIDS. Large population-based studies in transplant recipients have shown that a wider range of cancers could be associated with immune deficiency. Our aim was to compare cancer incidence in population-based cohort studies of people with HIV/AIDS and people immunosuppressed after solid organ transplantation.

METHODS

Two investigators independently identified eligible studies through searches of PubMed and reference lists. Random-effects meta-analyses of log standardised incidence ratios (SIRs) were calculated by type of cancer for both immune deficient populations.

FINDINGS

Seven studies of people with HIV/AIDS (n=444,172) and five of transplant recipients (n=31 977) were included. For 20 of the 28 types of cancer examined, there was a significantly increased incidence in both populations. Most of these were cancers with a known infectious cause, including all three types of AIDS-defining cancer, all HPV-related cancers, as well as Hodgkin's lymphoma (HIV/AIDS meta-analysis SIR 11.03, 95% CI 8.43-14.4; transplant 3.89, 2.42-6.26), liver cancer (HIV/AIDS 5.22, 3.32-8.20; transplant 2.13, 1.16-3.91), and stomach cancer (HIV/AIDS 1.90, 1.53-2.36; transplant 2.04, 1.49-2.79). Most common epithelial cancers did not occur at increased rates.

INTERPRETATION

The similarity of the pattern of increased risk of cancer in the two populations suggests that it is immune deficiency, rather than other risk factors for cancer, that is responsible for the increased risk. Infection-related cancer will probably become an increasingly important complication of long-term HIV infection.