Survival analysis in observational studies

Health And Performance Promotion in Youth (HAPPY) hybrid effectiveness-implementation cluster randomised trial: comparison of two strategies to implement an injury prevention exercise programme in Danish youth handball

OBJECTIVE

To investigate if a combination of an online and onsite implementation strategy was superior to an online-only strategy in enhancing the use of an injury prevention exercise programme (IPEP) and in reducing the risk of shoulder, knee and ankle injuries in youth community handball players (age 11-17) over a handball season.

METHODS

In this 30-week hybrid effectiveness-implementation cluster randomised type 3 study, 20 youth handball clubs were randomly assigned 1:1 to either a combined online and onsite implementation strategy (coach workshop using the health action process approach behaviour change model and health service provider (HSP) support) or an online-only strategy (control group). The primary implementation outcome was coach-reported adherence, measured as the average IPEP exercise usage by the team over 30 weeks. The primary effectiveness outcome was player-reported handball playing time to any new handball-related shoulder, knee and ankle injuries, reported weekly using the Oslo Sports Trauma Research Centre Questionnaire on Health Problems.

RESULTS

We enrolled 63 coaches (27% women) and 945 players (mean age 14.5 years, 55% girls). Intention-to-treat analyses showed no statistically significant difference between implementation strategies in adherence (between-group difference 1.4, 95% CI -0.5 to 3.4) or in cumulative injury risk (between-group difference 5.5% points, 95% CI -2.2 to 13.1).

CONCLUSION

Our findings demonstrate that in youth community handball, a combined online and onsite implementation strategy, including a coach workshop and HSP support, was not superior to an online-only strategy regarding adherence to an IPEP or in reducing shoulder, knee and ankle injury risk.

TRIAL REGISTRATION NUMBER

NCT05294237.

Association of Human Papillomavirus Status With Suicide Risk Among Patients With Head and Neck Cancer

Importance

Human papillomavirus (HPV) is strongly associated with head and neck cancer, and HPV status is considered a prognostic factor. Being a sexually transmitted infection, HPV-related cancers may have greater risk of stigma and psychological distress; however, the potential association of HPV-positive status with psychosocial outcomes, such as suicide, is understudied in head and neck cancer.

Objective

To investigate the association between HPV tumor status and suicide risk among patients with head and neck cancer.

Design, Setting, and Participants

This population-based retrospective cohort study included adult patients with clinically confirmed cases of head and neck cancer based on HPV tumor status from the Surveillance, Epidemiology, and End Results database from January 1, 2000, to December 31, 2018. Data analysis was conducted from February 1 to July 22, 2022.

Main Outcomes and Measures

The outcome of interest was death by suicide. Primary measure was HPV status of tumor site, dichotomized as positive or negative. Covariates included age, race, ethnicity, marital status, cancer stage at presentation, treatment modality, and type of residence. Cumulative risk of suicide among patients with HPV-positive and HPV-negative head and neck cancer was assessed using Fine and Gray competing risk models.

Results

Of 60 361 participants, the mean (SD) age was 61.2 (13.65) years, and 17 036 (28.2%) were women; there were 347 (0.6%) American Indian, 4369 (7.2%) Asian, 5226 (8.7%) Black, 414 (0.7%) Native Hawaiian or Other Pacific Islander, and 49 187 (81.5%) White individuals. A competing risk analysis showed a significant difference in the cumulative incidence of suicide between HPV-positive cancers (5-year suicide-specific mortality, 0.43%; 95% CI, 0.33%-0.55%) and HPV-negative cancers (5-year suicide-specific mortality, 0.24%; 95% CI, 0.19%-0.29%). Tumor status that was HPV positive was associated with increased suicide risk in the unadjusted model (hazard ratio [HR], 1.76; 95% CI, 1.28-2.40), but not the fully adjusted model (adjusted HR, 1.18; 95% CI, 0.79-1.79). Among people with oropharyngeal cancer only, HPV status was associated with increased suicide risk, but the width of the confidence interval prevented definitive conclusion (adjusted HR, 1.61; 95% CI 0.88-2.94).

Conclusions and Relevance

The results of this cohort study suggest that patients with HPV-positive head and neck cancer have similar risk of suicide as patients with HPV-negative cancer, despite differences in overall prognosis. Early mental health interventions may be associated with reduced suicide risk in all patients with head and neck cancer and should be assessed in future work.

Surgical intervention and patient factors associated with poor outcomes in patients with traumatic brain injury at a tertiary care hospital in Uganda

OBJECTIVE

The purpose of this study was to investigate whether neurosurgical intervention for traumatic brain injury (TBI) is associated with reduced risks of death and clinical deterioration in a low-income country with a relatively high neurosurgical capacity. The authors further aimed to assess whether the association between surgical intervention and acute poor outcomes differs according to TBI severity and various patient factors.

METHODS

Using TBI registry data collected from a national referral hospital in Uganda between July 2016 and April 2020, the authors performed Cox regression analyses of poor outcomes in admitted patients who did and did not undergo surgery for TBI, with surgery as a time-varying treatment variable. Patients were further stratified by TBI severity using the admission Glasgow Coma Scale (GCS) score: mild TBI (mTBI; GCS scores 13-15), moderate TBI (moTBI; GCS scores 9-12), and severe TBI (sTBI; GCS scores 3-8). Poor outcomes constituted Glasgow Outcome Scale scores 2-3, deterioration in TBI severity between admission and discharge (e.g., mTBI to sTBI), and death. Several clinical and demographic variables were included as covariates. Patients were observed for outcomes from admission through hospital day 10.

RESULTS

Of 1544 patients included in the cohort, 369 (24%) had undergone surgery. Rates of poor outcomes were 4% (n = 13) for surgical patients and 12% (n = 144) among nonsurgical patients (n = 1175). Surgery was associated with a 59% reduction in the hazard for a poor outcome (HR 0.41, 95% CI 0.23-0.72). Age, pupillary nonreactivity, fall injury, and TBI severity at admission were significant covariates. In models stratifying by TBI severity at admission, patients with mTBI had an 80% reduction in the hazard for a poor outcome with surgery (HR 0.20, 95% CI 0.04-0.90), whereas those with sTBI had a 65% reduction (HR 0.35, 95% CI 0.14-0.89). Patients with moTBI had a statistically nonsignificant 56% reduction in hazard (HR 0.44, 95% CI 0.17-1.17).

CONCLUSIONS

In this setting, the association between surgery and rates of poor outcomes varied with TBI severity and was influenced by several factors. Patients presenting with mTBI had the greatest reduction in the hazard for a poor outcome, followed by those presenting with sTBI. However, patients with moTBI had a nonsignificant reduction in the hazard, indicating greater variability in outcomes and underscoring the need for closer monitoring of this population. These results highlight the importance of accurate, timely clinical evaluation throughout a patient's admission and can inform decisions about whether and when to perform surgery for TBI when resources are limited.

Myeloablative conditioning for allo-HSCT in pediatric ALL: FTBI or chemotherapy?-A multicenter EBMT-PDWP study

Although most children with acute lymphoblastic leukemia (ALL) receive fractionated total body irradiation (FTBI) as myeloablative conditioning (MAC) for allogeneic hematopoietic stem cell transplantation (allo-HSCT), it is an important matter of debate if chemotherapy can effectively replace FTBI. To compare outcomes after FTBI versus chemotherapy-based conditioning (CC), we performed a retrospective EBMT registry study. Children aged 2–18 years after MAC for first allo-HSCT of bone marrow (BM) or peripheral blood stem cells (PBSC) from matched-related (MRD) or unrelated donors (UD) in first (CR1) or second remission (CR2) between 2000 and 2012 were included. Propensity score weighting was used to control pretreatment imbalances of the observed variables. 3.054 patients were analyzed. CR1 (1.498): median follow-up (FU) after FTBI (1.285) and CC (213) was 6.8 and 6.1 years. Survivals were not significantly different. CR2 (1.556): median FU after FTBI (1.345) and CC (211) was 6.2 years. Outcomes after FTBI were superior as compared with CC with regard to overall survival (OS), leukemia-free survival (LFS), relapse incidence (RI), and nonrelapse mortality (NRM). However, we must emphasize the preliminary character of the results of this retrospective “real-world-practice” study. These findings will be prospectively assessed in the ALL SCTped 2012 FORUM trial.

Associations of lack of voluntary private insurance and out-of-pocket expenditures with health inequalities. Evidence from an international longitudinal survey in countries with universal health coverage

Objectives

In countries with universal health coverage (UHC), national public health insurances cover 70% of health expenditures on average, but health care user fees and out-of-pocket expenditures have been neglected in empirical patient-centered health inequality research. This study is the first to investigate how health care-related factors are associated with health status among middle-aged and elderly people—vulnerable groups for the burden of illness—in countries with UHC.

Design

Longitudinal observational cohort study.

Setting

Population-based cohort Survey of Health, Ageing and Retirement in Europe (SHARE) in twelve countries with UHC.

Participants

Non-institutionalized people aged 50 and older (n = 29,260). Two subsamples were also used: participants without global activity limitation at baseline (n = 16,879) and participants without depression at baseline (n = 21,178).

Main outcome measures

Risk of death, risk of global activity limitations, and risk of depression. We used mixed-effects Cox proportional hazards regressions to estimate hazard ratios (HR) for all-cause mortality, physical limitations, and depression.

Results

Having a voluntary private insurance to cover health expenses not included in the public health care system (44.1% of the total sample) was a protective factor for all outcomes (HR≤0.91), controlling for a large range of socio-economic variables. On the contrary, having out-of-pocket expenditures (62.4%) was a risk factor (HR≥1.12).

Conclusions

UHC systems are not free from health inequalities: there is a potential effect of lack of voluntary private insurance and out-of-pocket expenditures on mortality and health. Health care-related factors should be at focus in future researches designed to understand and address health inequalities. Reducing out-of-pocket expenditures and developing voluntary private insurance may protect against premature illness and death.

Shedding Light on the Etiology of Sports Injuries: A Look Behind the Scenes of Time-to-Event Analyses

The etiological mechanism underpinning any sports-related injury is complex and multifactorial. Frequently, athletes perceive "excessive training" as the principal factor in their injury, an observation that is biologically plausible yet somewhat ambiguous. If the applied training load is suddenly increased, this may increase the risk for sports injury development, irrespective of the absolute amount of training. Indeed, little to no rigorous scientific evidence exists to support the hypothesis that fluctuations in training load, compared to absolute training load, are more important in explaining sports injury development. One reason for this could be that prospective data from scientific studies should be analyzed in a different manner. Time-to-event analysis is a useful statistical tool in which to analyze the influence of changing exposures on injury risk. However, the potential of time-to-event analysis remains insufficiently exploited in sports injury research. Therefore, the purpose of the present article was to present and discuss measures of association used in time-to-event analyses and to present the advanced concept of time-varying exposures and outcomes. In the paper, different measures of association, such as cumulative relative risk, cumulative risk difference, and the classical hazard rate ratio, are presented in a nontechnical manner, and suggestions for interpretation of study results are provided. To summarize, time-to-event analysis complements the statistical arsenal of sports injury prevention researchers, because it enables them to analyze the complex and highly dynamic reality of injury etiology, injury recurrence, and time to recovery across a range of sporting contexts.

Time to progression of pancreatic ductal adenocarcinoma from low-to-high tumour stages

OBJECTIVE

Although pancreatic ductal adenocarcinoma is considered a rapidly progressive disease, mathematical models estimate that it takes many years for an initiating pancreatic cancer cell to grow into an advanced stage cancer. In order to estimate the time it takes for a pancreatic cancer to progress through different tumor, node, metastasis (TNM) stages, we compared the mean age of patients with pancreatic cancers of different sizes and stages.

DESIGN

Patient age, tumour size, stage and demographic information were analysed for 13,131 patients with pancreatic ductal adenocarcinoma entered into the National Cancer Institute's Surveillance, Epidemiology and End Results (SEER) database. Multiple linear regression models for age were generated, adjusting for patient ethnicity, gender, tumour location and neoplastic grades.

RESULTS

African-American ethnicity and male gender were associated with an earlier age at diagnosis. Patients with stage I cancers (mean age 64.8 years) were on average 1.3 adjusted years younger at diagnosis than those with stage IV cancers (p=0.001). Among patients without distant metastases, those with T1 stage cancers were on average 1.06 and 1.19 adjusted years younger, respectively, than patients with T3 or T4 cancers (p=0.03 for both). Among patients with stage IIB cancers, those with T1/T2 cancers were 0.79 adjusted years younger than those with T3 cancers (p=0.06). There was no significant difference in the mean adjusted age of patients with stage IA versus stage IB cancers.

CONCLUSIONS

These results are consistent with the hypothesis that once pancreatic ductal adenocarcinomas become detectable clinically progression from low-stage to advanced-stage disease is rapid.

Decreased hazard of necrotizing enterocolitis in preterm neonates receiving red cell transfusions

BACKGROUND AND OBJECTIVES

Many observational studies reporting a temporal association between red cell transfusions (RBCTs) and necrotizing enterocolitis (NEC) in preterm infants fail to take into account RBCTs in infants without NEC. The objective of this study was to investigate the association between RBCTs and NEC in an analytical retrospective cohort study with minimization of selection and measurement bias and controlling for clinical covariates.

METHODS

Inborn preterm infants [23-32 weeks gestational age (GA)] without major congenital anomalies were eligible. Association of RBCT and modified Bell's Stage ≥2A NEC was explored using bivariate analyses and verified using multivariable Cox regression.

RESULTS

Of 627 eligible infants, 305 neither received RBCT nor developed NEC and 12 developed NEC prior to RBCT. Of 310 infants with RBCT, 27 developed NEC. Compared to infants without NEC, infants with NEC received significantly lower number of RBCTs before diagnosis of NEC (p = 0.000). On multivariable Cox regression controlling for clinical covariates, dichotomous RBCT exposure was associated with 60% reduced hazard for NEC.

CONCLUSIONS

RBCT exposure was associated with decreased hazards for NEC in preterm infants in this study; factors previously reported to be associated with NEC remained statistically significant predictors.

Risk of myocardial infarction and stroke in bipolar disorder: a systematic review and exploratory meta-analysis

OBJECTIVE

To review the evidence on and estimate the risk of myocardial infarction and stroke in bipolar disorder.

METHOD

A systematic search using MEDLINE, EMBASE, PsycINFO, Web of Science, Scopus, Cochrane Database of Systematic Reviews, and bibliographies (1946 - May, 2013) was conducted. Case-control and cohort studies of bipolar disorder patients age 15 or older with myocardial infarction or stroke as outcomes were included. Two independent reviewers extracted data and assessed quality. Estimates of effect were summarized using random-effects meta-analysis.

RESULTS

Five cohort studies including 13 115 911 participants (27 092 bipolar) were included. Due to the use of registers, different statistical methods, and inconsistent adjustment for confounders, there was significant methodological heterogeneity among studies. The exploratory meta-analysis yielded no evidence for a significant increase in the risk of myocardial infarction: [relative risk (RR): 1.09, 95% CI 0.96-1.24, P = 0.20; I(2)  = 6%]. While there was evidence of significant study heterogeneity, the risk of stroke in bipolar disorder was significantly increased (RR 1.74, 95% CI 1.29-2.35; P = 0.0003; I(2)  = 83%).

CONCLUSION

There may be a differential risk of myocardial infarction and stroke in patients with bipolar disorder. Confidence in these pooled estimates was limited by the small number of studies, significant heterogeneity and dissimilar methodological features.

Excessive progression in weekly running distance and risk of running-related injuries: an association which varies according to type of injury

STUDY DESIGN

An explorative, 1-year prospective cohort study. Objective To examine whether an association between a sudden change in weekly running distance and running-related injury varies according to injury type.

BACKGROUND

It is widely accepted that a sudden increase in running distance is strongly related to injury in runners. But the scientific knowledge supporting this assumption is limited.

METHODS

A volunteer sample of 874 healthy novice runners who started a self-structured running regimen were provided a global-positioning-system watch. After each running session during the study period, participants were categorized into 1 of the following exposure groups, based on the progression of their weekly running distance: less than 10% or regression, 10% to 30%, or more than 30%. The primary outcome was running-related injury.

RESULTS

A total of 202 runners sustained a running-related injury. Using Cox regression analysis, no statistically significant differences in injury rates were found across the 3 exposure groups. An increased rate of distance-related injuries (patellofemoral pain, iliotibial band syndrome, medial tibial stress syndrome, gluteus medius injury, greater trochanteric bursitis, injury to the tensor fascia latae, and patellar tendinopathy) existed in those who progressed their weekly running distance by more than 30% compared with those who progressed less than 10% (hazard ratio = 1.59; 95% confidence interval: 0.96, 2.66; P = .07).

CONCLUSION

Novice runners who progressed their running distance by more than 30% over a 2-week period seem to be more vulnerable to distance-related injuries than runners who increase their running distance by less than 10%. Owing to the exploratory nature of the present study, randomized controlled trials are needed to verify these results, and more experimental studies are needed to validate the assumptions. Still, novice runners may be well advised to progress their weekly distances by less than 30% per week over a 2-week period.

Risk of diabetes in children and adolescents exposed to antipsychotics: a nationwide 12-year case-control study

OBJECTIVE

Antipsychotics are associated with weight gain and diabetes. The risk and rate of diabetes in children and adolescents treated with antipsychotics is unclear.

METHOD

A longitudinal register linkage case-control study of diabetes in all psychiatric patients aged <18 years in Denmark was performed from January 1999 through the end of June 2010. Patients with and without antipsychotic exposure were compared regarding the occurrence of type 2 diabetes, defined as the prescription of oral antidiabetic medication. Regression analyses with type 2 diabetes as the dependent variable were conducted with sex, age, and diagnoses as covariates.

RESULTS

We compared the risk of diabetes in 48,299 psychiatrically ill youth. Of 7,253 youth exposed to antipsychotics, 52 (0.72%; 95% CI = 0.52% - 0.91%) developed type 2 diabetes. Of 41,046 youth without exposure to antipsychotics, 111 (0.27%; 95% CI = 0.22% - 0.32%) developed type 2 diabetes. In a 25,033 + 16,013 logistic regression analysis, type 2 diabetes development was associated with antipsychotic drug exposure (odds ratio [OR] = 1.60; 95% CI = 1.08 - 2.36, p < .05) female sex, (OR = 4.48; 95% CI = 2.90 - 6.91, p < 0.001) and older age at first psychiatric diagnosis (OR = 1.19; 95% CI = 1.12 - 1.27, p < 0.001), but not with psychiatric diagnosis. In a Cox-regression analysis, shorter time to type 2 diabetes onset was associated with female sex (Hazard Ratio (HR) = 4.83; 95% CI = 3.05-7.66, p = 0.001), and older age at first psychiatric diagnosis (HR = 1.19; 95% CI = 1.12-1.28, p = 0.001), while antipsychotic exposure (HR) = 1.41; 95% CI = 0.92-2.16, p = 0.11) trended towards increasing the rate of diabetes.

CONCLUSION

Antipsychotic treatment, female sex, and older age at psychiatric diagnosis were associated with a significantly more frequent type 2 diabetes onset in children and adolescents. Strict indications for antipsychotic treatment and routine cardiometabolic monitoring are crucial.

Developing a Weibull Model Extension to Estimate Cancer Latency

The mathematical model discussed in this paper presents a technique to estimate the length of the cancer’s silent growth period. The methodology described utilizes information obtained from observed cancer incidence to reconstruct what is cautiously believed to be the period of time from malignant cancer initiation to diagnosis. Analyses show a decreasing hazard for cancer indicating that the longer a patient survives, the more likely they are to reach the upper limit of their natural lifespan. Based on previous research, the Weibull distribution has been used to describe the mechanisms of cancer development. In contrast to the memoryless exponential distribution which assumes a constant failure rate, the shape of the Weibull distribution is dependent on past events and preserves a memory of prior survival. This provides a simple but powerful way to characterize how the unobserved experience of cancer relates to the observed as a function to estimate the time between onset and diagnosis. The results indicate a window of opportunity for early intervention when cancer is most treatable. The method presented provides useful information to identify cancers with high mortality and prolonged periods of undetected growth to distinguish types of dire public health concern.

Risk factors for invasive fungal disease after allogeneic hematopoietic stem cell transplantation: a single center experience

Invasive fungal disease (IFD) is a major cause of morbidity and mortality after hematopoietic stem cell transplantation (HCT). We performed a retrospective review of 271 adults with a hematologic malignancy undergoing allogeneic HCT to determine the incidence of and risk factors for IFD and to examine the impact of IFD on nonrelapse mortality and overall survival. We defined IFD using standard criteria and selected proven and probable cases for analysis. Diagnoses in the study group included acute leukemia (42%), non-Hodgkin lymphoma (24%), myelodysplastic syndrome (15%), chronic lymphocytic leukemia (5%), and other hematologic disorders (14%). Conditioning included reduced-intensity (64%) and myeloablative (36%) regimens. Donor sources were HLA-matched sibling (60%), matched unrelated (20%), haploidentical (12%), and cord blood (8%). A total of 51 episodes of IFD were observed in 42 subjects (15%). Aspergillus spp (47%) was the most frequent causative organism, followed by Candida spp (43%). The majority of IFD cases (67%) were reported after day +100 post-HCT. In multivariate analysis, haploidentical donor transplantation (hazard ratio [HR], 3.82; 95% confidence interval [CI], 1.49-9.77; P = .005) and grade II-IV acute graft-versus-host disease (HR, 2.55; 95% CI, 1.07-6.10; P = .03) were risk factors for the development of IFD. Conversely, higher infused CD34(+) cell dose was associated with a lower risk of IFD (HR, 0.80; 95% CI, 0.68-0.94; P = .006, per 1 × 10(6) cells/kg increase in CD34(+) cell infusion). IFD-related mortality was 33.3%. Nonrelapse mortality was significantly higher in patients who developed IFD compared with those without IFD (P < .001, log-rank test). Patients with IFD had lower overall survival (5.8 months versus 76.1 months; P < .001, log-rank test). Further studies exploring strategies to increase the infused cell dose and determine adequate prophylaxis, especially against aspergillus, beyond day +100 are needed.

Time-dependent study entries and exposures in cohort studies can easily be sources of different and avoidable types of bias

OBJECTIVES

To display and discuss the reasons and consequences of length and time-dependent bias. They might occur in presence of a time-dependent study entry or a time-dependent exposure which might change from unexposed to exposed.

STUDY DESIGN AND SETTING

Recalling the popular study of Oscar nominees and using a real-data example from hospital epidemiology, we give innovative and easy-to-understand graphical presentations of how these biases corrupt the analyses via distorted time-at-risk. Cumulative hazard plots and Cox proportional hazards models were used. We are building bridges to medical disciplines such as critical care medicine, hepatology, pharmaco-epidemiology, transplantation medicine, neurology, gynecology and cardiology.

RESULTS

In presence of time-dependent bias, the hazard ratio (comparing exposed with unexposed) is artificially underestimated. The length bias leads to an artificial underestimation of the overall hazard. When both biases coexist it can lead to different directions of biased hazard ratios.

CONCLUSION

Since length and time-dependent bias might occur in several medical disciplines, we conclude that understanding and awareness are the best prevention of survival bias.

Survival after diagnosis of hepatocellular carcinoma and potential impact of treatment in a hepatitis B or C infected cohort

AIM

  Little is known about the patterns of care and the impact of hepatocellular carcinoma (HCC) treatment on health outcomes at a population level. We conducted a population-based cohort study to examine HCC survival trends among people diagnosed with hepatitis B (HBV) or hepatitis C virus (HCV) infection, to determine predictors of receiving potentially curative therapy for HCC, and to examine the impact of HCC treatment on survival in New South Wales, Australia.

METHODS

  The Kaplan-Meier method was used to estimate survival, logistic regression to determine predictors of potentially curative therapy and Cox proportional hazards models to determine the impact of HCC treatment on survival. Years of potential life lost (YPLL) were calculated.

RESULTS

  During the period 1993-2007, 1081 cases of HCC were diagnosed. Median survival increased from 10.4 months during 1993-1997 to 18.4 months during 1998-2002, with no further improvement thereafter. Younger age at diagnosis (<65 years), being Asian-born and having multiple comorbid conditions increased the odds of receiving curative therapy. The effect of HCC treatment on the risk of mortality was similar between the HBV- and HCV-related HCC groups. Tumor-specific therapies had adjusted hazard ratios ranging 0.06-0.25 and palliative/supportive therapy alone had adjusted hazard ratios ranging 0.76-1.08. The average YPLL per person was 23.3.

CONCLUSION

  The burden of viral hepatitis-related HCC is substantial. Despite treatment advances in recent years, there has been no significant improvement in HCC survival. Efforts to improve HCC screening and early diagnosis are required to deliver curative treatment which clearly has a survival advantage.

The association between exit site infection and subsequent peritonitis among peritoneal dialysis patients

BACKGROUND AND OBJECTIVES

Peritonitis is the most common infectious complication seen in peritoneal dialysis (PD). Traditionally, exit site infection (ESI) has been thought to predispose PD patients to peritonitis, although the risks have not been quantified. This study aimed to quantify the risk of PD peritonitis after ESI.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

Data from 203 clinically stable PD patients >18 years of age who were followed as part of a randomized controlled trial over 18 months were used to estimate the risk of developing peritonitis within 30 days of an ESI compared with individuals who did not have a recent ESI. Sensitivity analyses were performed at 15, 45, and 60 days.

RESULTS

Patients were mostly male (64.5%) and Caucasian, with a mean age of 60.5 ± 14.4 years. There were 44 ESIs and 87 peritonitis episodes during the 18-month study. Seven patients had an ESI followed by peritonitis within 30 days. Using a frailty model, patients who had an ESI had a significantly higher risk of developing peritonitis within 30 days, even if the ESI was appropriately treated. This risk was maximal early on and diminished with time, with hazard ratios (95% confidence interval) of 11.1 at 15 days (HR=11.1, 95% CI=4.9-25.1), 5.3 at 45 days (2.5-11.3), and 4.9 at 60 days (2.4-9.9). In 2.3% of patients, subsequent peritonitis was caused by the same organism as the previous ESI.

CONCLUSIONS

A strong association between a treated ESI and subsequent PD peritonitis was present up to 60 days after initial diagnosis.

Distribution, size, and shape of abdominal aortic calcified deposits and their relationship to mortality in postmenopausal women

Abdominal aortic calcifications (AACs) correlate strongly with coronary artery calcifications and can be predictors of cardiovascular mortality. We investigated whether size, shape, and distribution of AACs are related to mortality and how such prognostic markers perform compared to the state-of-the-art AC24 marker introduced by Kauppila. Methods. For 308 postmenopausal women, we quantified the number of AAC and the percentage of the abdominal aorta that the lesions occupied in terms of their area, simulated plaque area, thickness, wall coverage, and length. We analysed inter-/intraobserver reproducibility and predictive ability of mortality after 8-9 years via Cox regression leading to hazard ratios (HRs). Results. The coefficient of variation was below 25% for all markers. The strongest individual predictors were the number of calcifications (HR = 2.4) and the simulated area percentage (HR = 2.96) of a calcified plaque, and, unlike AC24 (HR = 1.66), they allowed mortality prediction also after adjusting for traditional risk factors. In a combined Cox regression model, the strongest complementary predictors were the number of calcifications (HR = 2.76) and the area percentage (HR = −3.84). Conclusion. Morphometric markers of AAC quantified from radiographs may be a useful tool for screening and monitoring risk of CVD mortality.

Indexing disease progression at study entry with individuals at-risk for Huntington disease

The identification of clinical and biological markers of disease in persons at risk for Huntington disease (HD) has increased in efforts to better quantify and characterize the epoch of prodrome prior to clinical diagnosis. Such efforts are critical in the design and implementation of clinical trials for HD so that interventions can occur at a time most likely to increase neuronal survival and maximize daily functioning. A prime consideration in the examination of prodromal individuals is their proximity to diagnosis. It is necessary to quantify proximity so that individual differences in key marker variables can be properly interpreted. We take a data-driven approach to develop an index that can be viewed as a proxy for time to HD diagnosis known as the CAG-Age Product Scaled or CAP(S) . CAP(S) is an observed utility variable computed for all genetically at-risk individuals based on age at study entry and CAG repeat length. Results of a longitudinal receiver operating characteristic (ROC) analysis showed that CAP(S) had a relatively strong ability to predict individuals who became diagnosed, especially in the first 2 years. Bootstrap validation provided evidence that CAP(S) computed on a new sample from the same population could have similar discriminatory power. Cutoffs for the empirical CAP(S) distribution can be used to create a classification for mutation-positive individuals (Low-Med-High), which is, useful for comparison with the naturally occurring mutation-negative Control group. The classification is an improvement over the one currently in use as it is based on observed data rather than model-based estimated values. © 2011 Wiley-Liss, Inc.

VITAMIN SUPPLEMENTS AND RADIOGRAPHIC KNEE OSTEOARTHRITIS: THE CLEARWATER OSTEOARTHRITIS STUDY

Objective: To evaluate the association between vitamin supplements and the incidence and progression of radiographic knee osteoarthritis (OA). Study Design: Prospective cohort. Methods: Men and women aged 40 years and older (N = 2239) participating in the community-based Clearwater Osteoarthritis Study (1988–current) with biennial, sequential radiographs. The Lawrence & Kellgren ordinal scale was used to determine evidence of the study outcome, radiographic knee OA, and progression of radiographic knee OA. The study exposure was baseline history of self-reported vitamin supplement usage. Results: Individuals without baseline knee OA who self-reported vitamin supplement usage were 12% less likely to develop knee OA than were those individuals who self-reported no vitamin supplement usage (RR = 0.88; 95% C.I. 0.86–0.89). Those with baseline knee OA who self-reported vitamin supplement usage were 7% less likely to experience knee OA progression than were those individuals who self-reported no vitamin supplement usage (RR = 0.93; 95% C.I. 0.87–0.99). Conclusion: After consideration of BMI, gender, age, history of knee trauma, exercise and vitamin supplement usage prior to study baseline, these findings suggest that vitamin supplement usage may play a protective role in knee OA. Vitamin supplements may be a cost-effective strategy to reduce the incidence and/or slow the progression of knee OA. As many approved OA drugs are accompanied by adverse side effects, the role of vitamin supplements in the development and progression of knee OA warrants further investigation.

The effect of C1-esterase inhibitor on systemic inflammation in trauma patients with a femur fracture - The CAESAR study: study protocol for a randomized controlled trial

Background

Systemic inflammation in response to a femur fracture and the additional fixation is associated with inflammatory complications, such as acute respiratory distress syndrome and multiple organ dysfunction syndrome. The injury itself, but also the additional procedure of femoral fixation induces a release of pro-inflammatory cytokines such as interleukin-6. This results in an aggravation of the initial systemic inflammatory response, and can cause an increased risk for the development of inflammatory complications. Recent studies have shown that administration of the serum protein C1-esterase inhibitor can significantly reduce the release of circulating pro-inflammatory cytokines in response to acute systemic inflammation.

Objective

Attenuation of the surgery-induced additional systemic inflammatory response by perioperative treatment with C1-esterase inhibitor of trauma patients with a femur fracture.

Methods

The study is designed as a double-blind randomized placebo-controlled trial. Trauma patients with a femur fracture, Injury Severity Score ≥ 18 and age 18-80 years are included after obtaining informed consent. They are randomized for administration of 200 U/kg C1-esterase inhibitor intravenously or placebo (saline 0.9%) just before the start of the procedure of femoral fixation. The primary endpoint of the study is Δ interleukin-6, measured at t = 0, just before start of the femur fixation surgery and administration of C1-esterase inhibitor, and t = 6, 6 hours after administration of C1-esterase inhibitor and the femur fixation.

Conclusion

This study intents to identify C1-esterase inhibitor as a safe and potent anti-inflammatory agent, that is capable of suppressing systemic inflammation in trauma patients. This might facilitate early total care procedures by lowering the risk of inflammation in response to the surgical intervention. This could result in increased functional outcomes and reduced health care related costs.

Trial registration

clinicaltrials.gov NCT01275976 (January 12th 2011)

The effects of vitamin C supplementation on incident and progressive knee osteoarthritis: a longitudinal study

OBJECTIVE

To evaluate the association between vitamin C supplementation and the incidence and progression of radiographic knee osteoarthritis (OA).

DESIGN

Prospective cohort study.

SETTING

Clearwater Osteoarthritis Study (COS): (1988 to the present) a longitudinal study.

SUBJECTS

Male and female COS participants aged 40 years and above (n 1023). The study exposure was the participants' self-reported history of vitamin C supplementation. The participants underwent biennial, sequential knee radiographs, which were assessed using the Kellgren-Lawrence ordinal scale to determine evidence of the study 2 outcomes: incident radiographic knee OA (RKOA) and progression of RKOA.

RESULTS

Individuals without baseline knee OA who self-reported vitamin C supplement usage were 11% less likely to develop knee OA than were those individuals who self-reported no vitamin C supplement usage (risk ratio (RR)=0.89, 95% CI 0.85, 0.93). Among those participants with RKOA at baseline, vitamin C supplement usage did not demonstrate an association with RKOA progression (RR=0.94, 95% CI 0.79, 1.22).

CONCLUSIONS

In the present prospective cohort study, we found no evidence to support a protective role of vitamin C in the progression of knee OA. However, after controlling for confounding variables, these data suggest that vitamin C supplementation may indeed be beneficial in preventing incident knee OA. Given the massive public health burden of OA, the use of a simple, widely available and inexpensive supplement to potentially reduce the impact of this disease merits further consideration.

Lymphedema in breast cancer survivors: incidence, degree, time course, treatment, and symptoms

PURPOSE

To examine the incidence, degree, time course, treatment, and symptoms of lymphedema in breast cancer survivors.

METHODS

We conducted a 5-year, population-based prospective study of 631 randomly selected Philadelphia and Delaware County, Pennsylvania female residents with incident breast cancer who were diagnosed from 1999 to 2001. Using a questionnaire previously validated against physical therapists' measurement-based clinical criteria, we assigned a score indicating the degree of lymphedema (none, mild, or moderate/severe) to each month of follow-up based on the respondent's perceived differences in hand/arm size. Standard survival analysis methods permitted maximum use of follow-up.

RESULTS

Five-year cumulative incidence of lymphedema was 42 (42%) per 100 women. Among the 238 affected women, lymphedema first occurred within 2 years of diagnosis in 80% and within 3 years in 89%. Among 433 women observed for 3 years, 23% reported no more than mild lymphedema, 12% reported moderate/severe lymphedema, and 2% reported chronically moderate/severe lymphedema. Women with mild lymphedema were more than three times more likely to develop moderate/severe lymphedema than women with no lymphedema. Thirty-seven percent of women with mild lymphedema and 68% with moderate/severe lymphedema received treatment. Increasing proportions of women with increasing degree of lymphedema reported symptoms (eg, jewelry too tight, tired/thick/heavy arm). Symptoms present before the first occurrence of lymphedema were associated with a higher probability of later lymphedema (eg, hazard ratio for jewelry too tight = 7.37; 95% CI, 4.26 to 12.76).

CONCLUSION

Lymphedema after breast cancer is common but mostly mild. Subtle differences in self-reported hand/arm size and symptoms can be early signs of progressing lymphedema.

Does pharmacotherapy for attention-deficit/hyperactivity disorder predict risk of later major depression?

OBJECTIVE

This study's goal was to determine among youths with attention-deficit/hyperactivity disorder (ADHD) how the history of ADHD pharmacotherapy influenced the risk of developing major depressive disorder (MDD), compared to other commonly reported predictors.

METHOD

Diagnostic and treatment history data were analyzed retrospectively in 75 youths 11-18 years old with definite or probable ADHD, enrolled in an observational study at a tertiary mental health clinic. Subjects with histories of MDD (H/o MDD) (n = 36) were compared to others who had never been depressed (Never-Depressed) (n = 39) regarding histories of ADHD pharmacotherapy, psychopathology and other potential covariates of MDD risk.

RESULTS

H/o MDD subjects reported longer delays before initiating ADHD pharmacotherapy, were more often female, reported having experienced more traumatic event types, and had higher rates of early anxiety and externalizing disorders. With all covariates allowed to enter a backward stepwise Cox regression of survival time till first episodes of MDD, only two variables remained in the model. The time-dependent variable, ADHD pharmacotherapy, prolonged survival times (p = .012), while having experienced more traumatic event types shortened them (p = .001).

CONCLUSIONS

This study provides preliminary evidence that pharmacotherapy for ADHD may have a protective effect in ADHD youths, reducing the risk of later MDD.

A piecewise-constant Markov model and the effects of study design on the estimation of life expectancies in health and ill health

Multi-state models are frequently applied to describe transitions over time between three states: healthy, not healthy and death. The three-state model can be used to estimate life expectancies in health and ill health. In this article, continuous-time Markov models are specified for the transitions between the three states. Transition intensities are regressed on age as a time-dependent covariate. The covariate is handled in a piecewise-constant fashion where the time interval between two consecutive observations is divided into subintervals of fixed and equal lengths. Study design choices such as sample size, length of follow-up, and time intervals between observations are investigated in a simulation study. The effects on parameter estimation are discussed as well as the effects on the estimation of life expectancies. In addition, data taken from the UK Cognitive Functioning and Ageing Study are analysed.

Specificity of social anxiety disorder as a risk factor for alcohol and cannabis dependence

Social anxiety disorder (SAD) is highly comorbid with alcohol use disorders (AUDs) and cannabis dependence. However, the temporal sequencing of these disorders has not been extensively studied to determine whether SAD serves as a specific risk factor for problematic substance use. The present study examined these relationships after controlling for theoretically-relevant variables (e.g., gender, other Axis I pathology) in a longitudinal cohort over approximately 14 years. The sample was drawn from participants in the Oregon Adolescent Depression Project. After excluding those with substance use disorders at baseline, SAD at study entry was associated with 6.5 greater odds of cannabis dependence (but not abuse) and 4.5 greater odds of alcohol dependence (but not abuse) at follow-up after controlling for relevant variables (e.g., gender, depression, conduct disorder). The relationship between SAD and alcohol and cannabis dependence remained even after controlling for other anxiety disorders. Other anxiety disorders and mood disorders were not associated with subsequent cannabis or alcohol use disorder after controlling for relevant variables. Among the internalizing disorders, SAD appears to serve as a unique risk factor for the subsequent onset of cannabis and alcohol dependence.

Age and drug therapy are key prognostic factors for first clinical fracture in patients with primary osteoporosis

We evaluated the characteristics of 1,142 women and men who attended Canadian osteoporosis clinics and had T-score < or = -2.0 and no prior fractures to determine the predictors of first clinical fracture. Greater age and failure to start osteoporosis drug treatment increased the risk of first clinical fracture.

INTRODUCTION

Although risk factors for osteoporotic fractures are well-known, it is unclear which factors predict poor prognosis in patients with primary osteoporosis. The purpose of this study was to determine prognostic factors for first clinical fracture in patients with T-score < or = -2.0 and no previous clinical fracture.

METHODS

We examined prospectively collected data from 1,142 patients aged 40 and over in the Canadian Database of Osteoporosis and Osteopenia. We used prognosis methodology and performed survival analysis to determine factors that increase the risk of first clinical fracture.

RESULTS

Our inception cohort (mean age = 60.6 years, 91% females) had a cumulative fracture incidence of 5.1% (incidence rate: 2.53/100 person-years). Age and osteoporosis drug use predicted incident clinical fractures in multivariable regression analyses. The risk of first fracture increased by 3% per year. Failing to initiate osteoporosis treatment increased fracture risk by 2.4 times. In addition, low physical activity, high body mass index and low T-scores were found to predict fracture risk in certain patient subgroups using tree-structured survival analysis. These findings were robust and did not change with most sensitivity analyses.

CONCLUSION

Age and osteoporosis drug treatment are the main prognostic predictors of first clinical fracture in patients with T-score < or = -2.0.

Positive hindfoot valgus and osteoarthritis of the first metatarsophalangeal joint

BACKGROUND

The aim of this retrospective cohort study was to evaluate the association between increased hindfoot valgus and the subsequent development of osteoarthritis of the first metatarsophalangeal (MTP) joint. Specifically, our hypothesis was that among individuals free from first MTP joint osteoarthritis, those who have positive hindfoot valgus are more likely to develop first MTP joint osteoarthritis than are those individuals with normal hindfoot alignment.

METHODS

Our sample consisted of 1592 men and women, 40 years of age or older, participating in the Clearwater Osteoarthritis Study (1988 to 2001). Biennial physical examinations, including serial radiographs, were conducted. The Kellgren and Lawrence ordinal scale was used to determine radiographic evidence (grades 2+) of the study outcomes and incidence of first MTP joint osteoarthritis. Standing hindfoot valgus was assessed visually by a registered nurse, with a hindfoot valgus measurement of more than 5 degrees classified as a positive hindfoot valgus.

RESULTS

Individuals with hindfoot valgus were 23% more likely to subsequently develop first MTP joint osteoarthritis than were those without hindfoot malalignment (risk ratio = 1.23; p-value < 0.006). This risk estimate reflects the potential influence of age, gender, and body mass index.

CONCLUSIONS

Our data suggest that hindfoot valgus may increase the risk of developing foot osteoarthritis. The association of hindfoot valgus with first MTP joint osteoarthritis in this epidemiological assessment is supportive of the mechanical theory for the development of osteoarthritis. The authors speculate that future, related studies may determine that osteoarthritis prevention strategies can be broadened to include individuals with positive hindfoot valgus.

Survival after relapse in children with solid tumors: a follow-up study from the Italian off-therapy registry

BACKGROUND

Despite the increased survival of children with solid tumors, a significant proportion of cases still relapse following treatment discontinuation, and knowledge about the long-term outcome of this selected group of patients remains incomplete.

OBJECTIVE

To describe the long-term outcome of children treated for a solid tumor who relapsed after the elective end of therapy, and to explore factors associated with survival.

METHODS

All patients with the selected diagnoses-Hodgkin disease (HD), neuroblastoma (NB), tumor of the central nervous system (CNS), Wilms tumor (WT), or soft tissue sarcoma (STS)-enrolled in the Italian Pediatric Off-Therapy Registry in the period 1980-1998 were evaluated. Out of 3,927 patients, 694 had relapsed after treatment suspension; 639 were available for analysis. Survival and event-free survival were estimated by the Kaplan-Meier method. The log-rank test was used to assess differences in survival among the various types of cancer considered. Multivariate Cox proportional hazards analysis was adopted to explore possible prognostic factors.

RESULTS

There were 335 deaths: most of them (93%) were related to the primary cancer. The overall survival rate after relapse was 38% (95% CI 33-42) at 5 years, and 32% (95% CI 27-36%) at 15 years, while event free survival was 31% (95% CI 26-35) and 26% (95% CI 22-30%), respectively. There were significant differences according to the original diagnosis, with patients with HD doing better, and those with NB, CNS, and STS worse. No improvement of prognosis was evident over time. Post-relapse stem cell transplantation was associated with decreased risk of death only in the first year, not thereafter.

CONCLUSIONS

Overall, patients with solid tumors who relapse after treatment discontinuation have a poor outcome, but significant differences exist according to the tumor types.

Neonatal screening for cystic fibrosis does not affect time to first infection with Pseudomonas aeruginosa

OBJECTIVE

Newborn screening for cystic fibrosis was introduced in the Piedmont region of Italy in the year 2000. Our aim with this study was to estimate the effect of newborn screening on the risk of Pseudomonas aeruginosa infection at the regional cystic fibrosis pediatric reference center.

METHODS

The time to first infection with P aeruginosa within the historical cohort of cystic fibrosis children diagnosed between January 1, 1997, and June 30, 2004, was investigated, comparing survival functions and the adjusted hazard ratio of children diagnosed before and after newborn screening introduction. The role of pancreatic insufficiency was also concurrently investigated.

RESULTS

Overall, 71 children diagnosed with cystic fibrosis were identified, 27 cases were clinically diagnosed before newborn screening introduction, and 5 of them presented with meconium ileus, whereas 44 were identified by newborn screening. Among them 35 needed pancreatic enzyme supplementation, whereas 34 children were infected with P aeruginosa. Both the nonparametric and semiparametric survival estimates failed to show any significant increase in the risk of P aeruginosa infection among screened children compared with historical controls. However, the median time from cystic fibrosis diagnosis to P aeruginosa infection among screened children was significantly shorter (183 vs 448 days). Children with impaired pancreatic function were at high risk of P aeruginosa infection.

CONCLUSIONS

The results of the study suggest that health authorities should regard newborn screening for cystic fibrosis as an opportunity to improve care and outcomes among affected children and shift the focus from whether it is appropriate to screen to how to optimize biomedical and psychosocial outcomes of screening.

N-cadherin as a novel prognostic marker of progression in superficial urothelial tumors

PURPOSE

Loss of intercellular adhesion and increased cell motility promote tumor cell invasion and spreading. In bladder cancer, loss or reduced E-cadherin expression has been associated with poor survival, and aberrant expression of N-cadherin has been associated with the invasive phenotype of bladder carcinoma cells. The purpose of this study was to investigate whether N-cadherin expression was associated with the bladder tumor progression.

EXPERIMENTAL DESIGN

E-cadherin and N-cadherin expression was evaluated by immunohistochemistry in 101 tumors (pT1 and pT2-T3) and by reverse transcription-PCR analysis and immunohistochemistry in 28 other fresh frozen tumors (pT(a), pT1, and pT2-T3).

RESULTS

N-cadherin expression was absent in normal urothelium, appeared in stage pT1, and increased in pT2-pT3 tumors. In most cases, increased N-cadherin expression in invasive tumors was associated with loss of E-cadherin expression. Progression-free survival and multivariate analyses revealed that N-cadherin expression is an independent prognostic marker for pT1 tumor progression. Analysis of the 28 frozen tumors by immunohistochemistry and reverse transcription-PCR showed a good correlation between protein and gene expression in pT1 and pT2-T3 tumors. Interestingly, in pT(a) tumors, N-cadherin was not immunodetected, whereas mRNA was present in 50% of cases.

CONCLUSION

Regulatory defects in the N-cadherin promoter, abnormalities at the translational, or protein processing levels could explain the discrepancies between protein and mRNA expression. Most importantly, this study identified N-cadherin as a novel prognostic marker of progression in superficial urothelial tumors. Clearly, N-cadherin acts in an invasive mode in bladder cancer, but whether it has a primary role in urothelial neoplastic progression has yet to be investigated.

Mortality in African-Americans with Type 1 diabetes: The New Jersey 725

AIM

To determine rates and risk factors for all-cause mortality in African-Americans with Type 1 diabetes from a 3-year observational follow-up study of 725 African-Americans with Type 1 diabetes conducted between 1 January 1999 and 31 December 2001.

METHODS

Date of death was ascertained either from telephone contact with the patient's family or from relatives or on line review of the US Social Security death index.

RESULTS

Since the initial examination, 131 (18.1%) patients, 60 (20%) men and 71 (17%) women, have died. At the time of death, the mean age of the men was 40.7 +/- 10.6 years and that of the women 39.4 +/- 10.5 years. The median duration of diabetes at the baseline examination was 8.04 years, interquartile range (IQR) 3.76-15.22 years for men and median 10.54, IQR 4.49-18.36 years for women. Three-year mortality rates were 7.1% for women and 10.6% for men. Age-adjusted mortality rates were not significantly different between men and women. Relative to the general US and the New Jersey African-American population, standardized mortality ratios of African-Americans with Type 1 diabetes were 12 and six times greater for women and men, respectively. Older age, low socio-economic status, low body mass index, high diastolic blood pressure, macroangiopathy, proteinuria, severe diabetic retinopathy and heavy alcohol consumption were independent risk factors for all-cause mortality. In patients with microproteinuria at initial examination, the mortality rate for men was twice that of women.

CONCLUSION

Microproteinuria and other potentially modifiable factors, including hypertension, macroangiopathy and heavy alcohol consumption, are independent risk factors for mortality in this ethnic group.

Effect of Study Setting on Anticoagulation Control

BACKGROUND

For patients receiving therapy with oral anticoagulants (OACs), the proportion of time spent in the therapeutic range (ie, anticoagulation control) is strongly associated with bleeding and thromboembolic risk. The effect of study-level factors, especially study setting, on anticoagulation control is unknown.

OBJECTIVES

Describe anticoagulation control achieved in the published literature. We also used metaregressive techniques to determine which study-level factors significantly influenced anticoagulation control.

STUDIES

All published randomized or cohort studies that measured international normalized ratios (INRs) serially in anticoagulated patients and reported the proportion of time between INRs ranging from 1.8 to 2.0 and 3.0 to 3.5.

RESULTS

We identified 67 studies with 123 patient groups having 50,208 patients followed for a total of 57,154.7 patient-years. A total of 68.3% of groups were from anticoagulation clinics, 7.3% were from clinical trials, and 24.4% were from community practices. Overall, patients were therapeutic 63.6% of time (95% confidence interval [CI], 61.6 to 65.6). In the metaregression model, study setting had the greatest effect on anticoagulation control with studies in community practices having significantly lower control than either anticoagulation clinics or clinical trials (-12.2%; 95% CI, -19.5 to -4.8; p < 0.0001). Self-management was associated with a significant improvement of time spent in the therapeutic range (+7.0%; 95% CI, 0.7 to 13.3; p = 0.03).

CONCLUSIONS

Patients who have received anticoagulation therapy spend a significant proportion of their time with an INR out of the therapeutic range. Patients from community practices showed significantly worse anticoagulation control than those from anticoagulation clinics or clinical trials. This should be considered when interpreting the results of, and generalizing from, studies involving OACs.

Economic evaluation of treating chronic obstructive pulmonary disease with inhaled corticosteroids and long-acting beta2-agonists in a health maintenance organization

OBJECTIVES

In light of recent results from observational studies showing prolonged survival in subjects taking long-acting beta2-agonists (LABA) and/or inhaled corticosteroids (ICS) for chronic obstructive pulmonary disease (COPD), we investigated their cost-effectiveness (CE).

METHODS

Costs and survival data were collected for a sample of members enrolled in a large Health Maintenance Organization in the United States. An observational study design was used to evaluate cumulative costs and health benefits of LABA, ICS, ICS+LABA, or comparison drugs. Survival was estimated using a parametric regression model. Costs were adjusted for censoring and prognostic factors. CE was evaluated over a time horizon of 36 months and the remaining lifetime of subjects.

RESULTS

Over 36 months, life expectancy and costs were: 2.4 years (95% confidence interval (CI): 2.3; 2.5) and $28,030 (CI: $23,400; $33,570) for not receiving ICS or LABA; 2.6 years (CI: 2.6; 2.7) and $35,170 (CI: $29,970; $40,620) for ICS alone; 2.6 years (CI: 2.5; 2.7) and $27,380 (CI: $21,780; $32,510) for LABA alone; and, 2.7 years (CI: 2.6; 2.8) and $33,780 (CI: $28,700; $39,440) for subjects treated with ICS+LABA. The lifetime analysis showed similar trends.

CONCLUSIONS

There is an acute need to find effective, life-extending treatments for persons with COPD. ICS, LABA or their combination represent promising treatment options and are currently being tested in randomized trials. If the impact on survival seen in these trials compares to that seen in observational studies, LABA and the combination treatment are likely to be cost-effective in the United States.