Validity of a prescription claims database to estimate medication adherence in older persons

How to use pharmacy claims data to measure patient nonadherence? The example of oral diabetics in therapy of type 2 diabetes mellitus

INTRODUCTION

The purpose of this study was to describe the methodological framework underlying nonadherence (NA) measurement based on pharmacy claims data, its quantitative impact on the results of NA studies, and to identify those methodological categories most likely to explain diabetes-related clinical outcomes. We use the example of oral antidiabetics in the treatment of diabetes mellitus type 2; 113,108 patients derived from a German statutory health insurance fund were analyzed.

METHODS

We identified 12 methodological categories as pervasive features in pharmacy claims data based NA analyses. The influence of the different methodological categories and their parameters on analysis results was tested using sensitivity analysis. To validate alternative methodological framework options, we performed multivariate logistical regression estimates using diabetes-related hospitalization/clinical events as a combined dichotomized dependent variable.

RESULTS

The choice of parameters within the identified 12 methodological categories available has exceptional impact on the results of pharmacy data based claims NA analyses. When the full range of theoretically possible cases is considered in our sample, it can be seen that the resulting NA range is between 15.7% and 97.0%. The definition of the required daily dose, the decision to use either a prescription-/interval-based approach, and the classes of medication analyzed exert a notable influence on the study results. In our analysis, 69.4% of the 216 different study design options analyzed significantly explain the likelihood of diabetes-related clinical events.

CONCLUSIONS

We recommend strongly that methodological transparency is awarded a much more important role in the conduct of NA analyses made on the basis of pharmacy claims data.

Variation in the days supply field for osteoporosis medications in Ontario

We examined pharmacy claims for osteoporosis medications dispensed in the community (78 %) and long-term care (LTC) to determine if days supply values matched expected dosing intervals. Results identify potential reporting errors that can have implications for drug exposure misclassification, particularly in LTC where only 59 % of reported values matched expected values.

INTRODUCTION

The days supply field is commonly used to examine patterns of drug utilization and classify drug exposure, yet its accuracy has received little attention. We sought to describe the days supply reported for osteoporosis drugs and examine if values matched expected therapeutic dosing intervals.

METHODS

We examined days supply values for osteoporosis medications submitted to the Ontario Drug Benefits program for seniors, 1997-2011. Days supply values were evaluated by dosing regimen and setting (community or long-term care [LTC]) and compared to pre-defined expected values. We defined expected days supply by the therapeutic dosing interval: daily in 7- or 30-day intervals, or as 100 days; weekly in 7- or 30-day intervals; monthly and daily nasal spray in 28- or 30-day intervals; and cyclical etidronate as a 90-day supply.

RESULTS

We identified 17,615,404 osteoporosis prescriptions, with 78 % dispensed in the community. Most daily oral prescriptions were dispensed by an expected therapeutic dosing interval (97 %). Annual IV zoledronic acid was most commonly dispensed as a 1-day supply (62 %). Distinct differences in agreement were observed for other regimens, with the expected days supply more commonly reported in community versus LTC: cyclical etidronate (86 % vs. 40 %), weekly (91 % vs. 60 %), monthly (94 % vs. 35 %), and nasal spray (84 % vs. 40 %).

CONCLUSIONS

Results suggest that inaccuracies in the days supply field exist, particularly among prescriptions dispensed in LTC. Inaccurate reporting may have significant implications for osteoporosis drug exposure misclassification.

The association between market availability and adherence to antihypertensive medications: an observational study

BACKGROUND

High adherence to angiotensin-converting enzyme inhibitors (ACEIs) and angiotensin receptor blockers (ARBs) reported in observational studies has frequently been attributed to improved tolerability. However, these agents are also relatively new to the market compared to other antihypertensive medications. We aimed to determine if an association exists between adherence and market availability of a specific antihypertensive agent.

METHODS

This retrospective cohort study used administrative data from Saskatchewan, Canada. Subjects were ≥40 years of age and received a new antihypertensive medication between 1994 and 2002. The primary outcome was the proportion of subjects achieving optimal adherence (≥80%) at 1 year, stratified by antihypertensive medication class and the year of availability. Adherence was measured using the cumulative mean gap ratio.

RESULTS

A total of 36,214 subjects met the inclusion criteria. Optimal adherence was observed in 4987 of 8623 (57.8%) subjects receiving ACEIs and 1013 of 1600 (63.3%) subjects receiving ARBs, but adherence appeared inconsistent when examined within each antihypertensive class. A pattern of increasing mean adherence was observed according to availability in the ACEI subgroup (Spearman r = 0.82; P = 0.007) but not the ARB subgroup (Spearman r = 0.41; P = 0.49). However, the association between availability and optimal adherence converged when ARB and ACEI users were combined (Spearman r = 0.85, P < 0.001).

CONCLUSIONS

Optimal adherence with ACEIs and ARBs compared to other antihypertensive agents may be associated with their relative availability. To what extent optimal adherence is also associated with improved tolerability, as currently believed, remains to be determined.

Comparative effectiveness of sulfonylurea and metformin monotherapy on cardiovascular events in type 2 diabetes mellitus: a cohort study

BACKGROUND

The effects of sulfonylureas and metformin on outcomes of cardiovascular disease (CVD) in type 2 diabetes are not well-characterized.

OBJECTIVE

To compare the effects of sulfonylureas and metformin on CVD outcomes (acute myocardial infarction and stroke) or death.

DESIGN

Retrospective cohort study.

SETTING

National Veterans Health Administration databases linked to Medicare files.

PATIENTS

Veterans who initiated metformin or sulfonylurea therapy for diabetes. Patients with chronic kidney disease or serious medical illness were excluded.

MEASUREMENTS

Composite outcome of hospitalization for acute myocardial infarction or stroke, or death, adjusted for baseline demographic characteristics; medications; cholesterol, hemoglobin A1c, and serum creatinine levels; blood pressure; body mass index; health care utilization; and comorbid conditions.

RESULTS

Among 253 690 patients initiating treatment (98 665 with sulfonylurea therapy and 155 025 with metformin therapy), crude rates of the composite outcome were 18.2 per 1000 person-years in sulfonylurea users and 10.4 per 1000 person-years in metformin users (adjusted incidence rate difference, 2.2 [95% CI, 1.4 to 3.0] more CVD events with sulfonylureas per 1000 person-years; adjusted hazard ratio [aHR], 1.21 [CI, 1.13 to 1.30]). Results were consistent for both glyburide (aHR, 1.26 [CI, 1.16 to 1.37]) and glipizide (aHR, 1.15 [CI, 1.06 to 1.26]) in subgroups by CVD history, age, body mass index, and albuminuria; in a propensity score-matched cohort analysis; and in sensitivity analyses.

LIMITATION

Most of the veterans in the study population were white men; data on women and minority groups were limited but reflective of the Veterans Health Administration population.

CONCLUSION

Use of sulfonylureas compared with metformin for initial treatment of diabetes was associated with an increased hazard of CVD events or death.

PRIMARY FUNDING SOURCE

Agency for Healthcare Research and Quality and the U.S. Department of Health and Human Services.

Initiation of sulfonylureas versus metformin is associated with higher blood pressure at one year

PURPOSE

To determine if incident oral antidiabetic drug (OAD) use was associated with 12-month systolic blood pressure (BP) and if this was mediated through body mass index (BMI) changes.

METHODS

A retrospective cohort of veterans with hypertension who initiated metformin (n = 2057) or sulfonylurea (n = 1494) between 1 January 2000 and 31 December 2007 in the Veterans Administration Mid-South Network was assembled. Patients were included if they had complete covariates, including 12-month BP and BMI, and persisted on therapy for 12 months. Linear regression was conducted to investigate the effect of OADs on 12-month systolic BP adjusting for demographics, glycated hemoglobin, creatinine, BMI, health care utilization, and comorbidities, including cardiovascular disease (CVD). A second analysis examined if these effects were mediated by BMI change. The secondary outcome was the proportion of patients who had a controlled BP (≤ 140/90 mmHg) at 12 months adjusted for baseline BP and covariates.

RESULTS

Patients were white (82%) males (97%) with median age of 64 years (interquartile range [IQR] 57, 72), and 27% had history of CVD. Sulfonylurea users had a 1.33 mmHg (0.16, 2.50, p = 0.03) higher 12-month systolic BP than metformin users. The median change in BMI from OAD initiation to 12 months was -0.76 (IQR -1.78, 0.07) and 0.21 (IQR -0.57, 1.03) among metformin and sulfonylurea users, respectively. In a model adjusting for BMI change, the difference in 12-month systolic BP between sulfonylurea and metformin users became insignificant (0.23 (-1.00, 1.45), p = 0.72), while one BMI unit change was associated with an increase in 12-month systolic BP of 1.07 mmHg (0.74, 1.40, p < 0.0001). At 12 months, 68.3% of metformin patients had controlled BP versus 64.2% of sulfonylurea patients (p = 0.01).

CONCLUSIONS

Compared with metformin, sulfonylurea initiation was associated with increased systolic BP at 12 months, which appears to be mediated by the differential effects of these drugs on BMI.

First-fill medication discontinuations and nonadherence to antihypertensive therapy: an observational study

BACKGROUND

Medication nonadherence is a barrier to successfully managing hypertension, but little is known about the contribution that immediate discontinuations have on antihypertensive (AHT) nonadherence. The purpose of this study was to determine the proportion of new AHT users who discontinue after a single dispensation, and to examine potential predictors of these discontinuations.

METHODS

This retrospective cohort study utilizing linked administrative data from Saskatchewan, Canada. Subjects were ≥40 years of age and received a new AHT between 1994-2002. The primary end point was the proportion of subjects who discontinued their AHT after the first dispensation (first-fill discontinuation). The proportion of nonadherence attributed to first-fill discontinuations was then calculated. Multivariate regression identified factors associated with first-fill discontinuations.

RESULTS

52,039 subjects were included in the analyses. Mean age was 59.4 (s.d. 12.5) years, and 42% were male. Overall, 25,812/52,039 (50%) subjects were nonadherent at 1 year; first-fill discontinuations accounted for 39.1% (10,081/25,812) of this nonadherence. Approximately 20% (10,081/52,039) of all subjects discontinued all AHT therapy after the first fill. A higher chronic disease score (adjusted odds ratio (OR) 1.09, 95% confidence interval (CI) 1.08-1.11) and antidepressant medication usage during the observation year (adjusted OR 1.17, 95% CI 1.09-1.26) was associated with increased risk for first-fill discontinuations. Older age, starting AHT therapy after 1994, frequent physician visits, or use of a statin, acetylsalicylic acid, warfarin or antihyperglycemic during the observation year was associated with a lower risk for first-fill discontinuations.

CONCLUSION

A substantial proportion of nonadherence to AHT medications is due to discontinuations after only a single dispensation.

Correspondence between general practitioner-reported medication use and timing of prescription dispensation

Epidemiologic studies often rely on drug dispensation records to measure medication intake. We aimed to estimate correspondence between general practitioner (GP)-reported treatment and timing of prescription dispensation. From seven GPs in northern Denmark, we obtained 317 prescription records for 286 patients treated with ten commonly prescribed medication types for chronic diseases. We linked the GP-reported information to the regional prescription database to retrieve patients’ prescription records both prospectively and retrospectively in relation to the GP-reported date of treatment (index date, August 20, 2008 for all patients). We computed overall and medication-specific correspondence between GP-reported treatment and the timing of dispensation. We computed correspondence based on both exact medication and therapeutic subgroup agreement. The correspondence for dispensation within ±90 days of GP-reported treatment was 0.81 (95% confidence interval = 0.76–0.85) with variation by medication type, ranging from 0.55 for ACE-inhibitors to 1.00 for oral glucose-lowering agents. The correspondence was greater when analyzed within therapeutic groups than when analyzed for exact medications within these groups.

Antidepressant treatment and adherence to antiretroviral medications among privately insured persons with HIV/AIDS

In order to examine relationships between depression treatments (antidepressant and/or psychotherapy utilization) and adherence to antiretroviral therapy (ART), we conducted a retrospective analysis of medical and pharmacy insurance claims for privately insured persons living with HIV/AIDS (PLWHA) diagnosed with depression (n = 1,150). Participants were enrolled in 80 insurance plans from all 50 states. Adherence was suboptimal. Depression treatment initiators were significantly more likely to be adherent to ART than the untreated. We did not observe an association between psychotherapy utilization and ART adherence, yet given the limitations of the data (e.g., there is no information on types of psychological treatment and its targets), the lack of association should not be interpreted as lack of efficacy.

Predictors of decline in medication adherence: results from the cohort study of medication adherence among older adults

Few data are available on the predictors of decline in antihypertensive medication adherence and the association of decline in adherence with subsequent blood pressure (BP) control. The current analysis included 1965 adults from the Cohort Study of Medication Adherence Among Older Adults recruited between August 2006 and September 2007. Decline in antihypertensive medication adherence was defined as a ≥2-point decrease on the 8-item Morisky Medication Adherence Scale assessed during telephone surveys 1 and 2 years after baseline. Risk factors for decline in adherence were collected using telephone surveys and administrative databases. BP was abstracted from outpatient records. The annual rate for a decline in adherence was 4.3% (159 participants experienced a decline). After multivariable adjustment, a decline in adherence was associated with an odds ratio (OR) for uncontrolled BP (≥140/90 mm Hg) at follow-up of 1.68 (95% CI: 1.01-2.80). Depressive symptoms (OR: 1.84 [95% CI: 1.20-2.82]) and a high stressful life events score (OR: 1.68 [95% CI: 1.19-2.38]) were associated with higher ORs for a decline in adherence. Female sex (OR: 0.61 [95% CI: 0.42-0.88]), being married (OR: 0.68 [95% CI: 0.47-0.98]), and calcium channel blocker use (OR: 0.68 [95% CI: 0.48-0.97]) were associated with lower ORs for decline. In summary, a decline in antihypertensive medication adherence was associated with uncontrolled BP. Modifiable factors associated with decline were identified. Further research is warranted to determine whether interventions can prevent the decline in antihypertensive medication adherence and improve BP control.

Comparative effectiveness of antibiotic treatment strategies for pediatric skin and soft-tissue infections

OBJECTIVE

To compare the effectiveness of clindamycin, trimethoprim-sulfamethoxazole, and β-lactams for the treatment of pediatric skin and soft-tissue infections (SSTIs).

METHODS

A retrospective cohort of children 0 to 17 years of age who were enrolled in Tennessee Medicaid, experienced an incident SSTI between 2004 and 2007, and received treatment with clindamycin (reference), trimethoprim-sulfamethoxazole, or a β-lactam was created. Outcomes included treatment failure and recurrence, defined as an SSTI within 14 days and between 15 and 365 days after the incident SSTI, respectively. Adjusted models stratified according to drainage status were used to estimate the risk of treatment failure and time to recurrence.

RESULTS

Among the 6407 children who underwent drainage, there were 568 treatment failures (8.9%) and 994 recurrences (22.8%). The adjusted odds ratios for treatment failure were 1.92 (95% confidence interval [CI]: 1.49-2.47) for trimethoprim-sulfamethoxazole and 2.23 (95% CI: 1.71-2.90) for β-lactams. The adjusted hazard ratios for recurrence were 1.26 (95% CI: 1.06-1.49) for trimethoprim-sulfamethoxazole and 1.42 (95% CI: 1.19-1.69) for β-lactams. Among the 41 094 children without a drainage procedure, there were 2435 treatment failures (5.9%) and 5436 recurrences (18.2%). The adjusted odds ratios for treatment failure were 1.67 (95% CI: 1.44-1.95) for trimethoprim-sulfamethoxazole and 1.22 (95% CI: 1.06-1.41) for β-lactams; the adjusted hazard ratios for recurrence were 1.30 (95% CI: 1.18-1.44) for trimethoprim-sulfamethoxazole and 1.08 (95% CI: 0.99-1.18) for β-lactams.

CONCLUSIONS

Compared with clindamycin, use of trimethoprim-sulfamethoxazole or β-lactams was associated with increased risks of treatment failure and recurrence. Associations were stronger for those with a drainage procedure.

Potential and pitfalls of using large administrative claims data to study the safety of osteoporosis therapies

Long-term bisphosphonate use may be associated with several rare adverse events. Such associations are not optimally evaluated in conventional randomized controlled trials due to the requirements of large numbers of patients and long-term follow-up. Alternatively, administrative claims data from various sources such as Medicare have been used. Because claims data are collected for billing and reimbursement purposes, they have limitations, including uncertain diagnostic validity and lack of detailed clinical information. Using such data for pharmacoepidemiologic research requires complex methodologies that may be less familiar to many researchers and clinicians. In this review, we discuss the strengths and limitations of using claims data for osteoporosis drug safety research, summarize recent advancements in methodologies that may be used to address the limitations, and present directions for future research using claims data.

Adherence with statins in a real-life setting is better when associated cardiovascular risk factors increase: a cohort study

BACKGROUND

While the factors for poor adherence for treatment with statins have been highlighted, the impact of their combination on adherence is not clear.

AIMS

To estimate adherence for statins and whether it differs according to the number of cardiovascular risk factors.

METHODS

A cohort study was conducted using data from the main French national health insurance system reimbursement database. Newly treated patients with statins between September 1 and December 31, 2004 were included. Patients were followed up 15 months. The cohort was split into three groups according to their number of additional cardiovascular risk factors that included age and gender, diabetes mellitus and cardiovascular disease (using co-medications as a proxy). Adherence was assessed for each group by using four parameters: (i) proportion of days covered by statins, (ii) regularity of the treatment over time, (iii) persistence, and (iv) the refill delay.

RESULTS

16,397 newly treated patients were identified. Of these statin users, 21.7% did not have additional cardiovascular risk factors. Thirty-one percent had two cardiovascular risk factors and 47% had at least three risk factors. All the parameters showed a sub-optimal adherence whatever the group: days covered ranged from 56% to 72%, regularity ranged from 23% to 33% and persistence ranged from 44% to 59%, but adherence was better for those with a higher number of cardiovascular risk factors.

CONCLUSIONS

The results confirm that long-term drug treatments are a difficult challenge, particularly in patients at lower risk and invite to the development of therapeutic education.

Pharmacokinetically and clinician-determined adherence to an antidepressant regimen and clinical outcome in the TORDIA trial

OBJECTIVE

Nonadherence to antidepressant treatment may contribute to poor outcome and to suicidal adverse events in adolescent depression. We examine the relationship between adherence and both clinical response and suicidal events in participants in the Treatment of Resistant Depression in Adolescents (TORDIA) study.

METHOD

The relationship between adherence to medication and clinical outcome was assessed in 190 treatment-resistant depressed adolescents who were randomized to one of four cells: switch to another selective serotonin reuptake inhibitor (SSRI), switch to venlafaxine, or either of these two medication switches plus cognitive behavioral therapy. Plasma levels of antidepressant drug and metabolites were determined after 6 and 12 weeks of treatment. A twofold or greater variation in the dose-adjusted concentration of drug plus metabolites (level/dose ratio [LDR]) was defined as nonadherence. Nonadherence was also determined by clinician pill counts (CPC) of the proportion of prescribed pills that were unused and was defined as having greater than 30% of the prescribed pills remaining.

RESULTS

LDR and CPC showed low concordance. LDR was unrelated to clinical response. CPC adherence was related to a higher response rate overall (adherent, 63.0% versus nonadherent, 47.2%, p = .03). Approximately half (50.8%) of the sample surveyed showed evidence of nonadherence by CPC. Neither measure of adherence was related to the occurrence of suicidal events or to the pace of decline in suicidal ideation.

CONCLUSIONS

Clinician pill counts may be a relevant measure of adherence that is related to outcome under formal clinical trial conditions in depressed adolescents. Nonadherence appears to be a common and significant source of treatment nonresponse. Clinical Trial Registration Information-Treatment of SSRI-Resistant Depression in Adolescents (TORDIA); http://www.clinicaltrials.gov; NCT00018902.

Medication adherence among community-dwelling patients with heart failure

OBJECTIVE

To determine medication use and adherence among community-dwelling patients with heart failure (HF).

PATIENTS AND METHODS

Residents of Olmsted County, Minnesota, with HF were recruited from October 10, 2007, through February 25, 2009. Pharmacy records were obtained for the 6 months after enrollment. Medication adherence was measured by the proportion of days covered (PDC). A PDC of less than 80% was classified as poor adherence. Factors associated with medication adherence were investigated.

RESULTS

Among the 209 study patients with HF, 123 (59%) were male, and the mean ± SD age was 73.7 ± 13.5 years. The median (interquartile range) number of unique medications filled during the 6-month study period was 11 (8-17). Patients with a documented medication allergy were excluded from eligibility for medication use within that medication class. Most patients received conventional HF therapy: 70% (147/209) were treated with β-blockers and 75% (149/200) with angiotensin-converting enzyme inhibitors or angiotensin II receptor blockers. Most patients (62%; 127/205) also took statins. After exclusion of patients with missing dosage information, the proportion of those with poor adherence was 19% (27/140), 19% (28/144), and 13% (16/121) for β-blockers, angiotensin-converting enzyme inhibitors or angiotensin II receptor blockers, and statins, respectively. Self-reported data indicated that those with poor adherence experienced more cost-related medication issues. For example, those who adhered poorly to statin therapy more frequently reported stopping a prescription because of cost than those with good adherence (46% vs 6%; P < .001), skipping doses to save money (23% vs 3%; P = .03), and not filling a new prescription because of cost (46% vs 6%; P < .001).

CONCLUSION

Community-dwelling patients with HF take a large number of medications. Medication adherence was suboptimal in many patients, often because of cost.

Glycemic and weight changes after persistent use of incident oral diabetes therapy: a Veterans Administration retrospective cohort study

PURPOSE

Systematic reviews have reported that sulfonylureas and metformin were as effective in reducing hemoglobin A1c (A1C) as other oral antidiabetic drugs (OADs) in clinical trial populations. Data on comparative effectiveness of OADs in other populations is limited. The objective was to compare the effectiveness of incident OAD regimens in reducing A1C and to compare the effect of OADs on body mass index (BMI).

METHODS

Retrospective cohort study using data from the Veterans Affairs Mid-South network (2001-2007). Of 18 205 veterans who filled 19 511 incident OAD prescriptions, 2096 had complete covariates, persisted on their incident treatment for 12 months, and had baseline and 12-month A1C values. For the BMI analysis, 2484 patients had complete information. Incident OAD regimens included metformin and sulfonylureas. Primary outcomes were 12-month A1C and BMI, which were compared controlling for demographic characteristics, baseline A1C and BMI, psychiatric diagnoses, and healthcare utilization.

RESULTS

Median [interquartile range (IQR)] A1C decreased from 7.1% [6.5, 7.8] at baseline to 6.5% [6.0, 7.0] at 12 months. Twelve month-A1C in sulfonylurea users was similar to metformin users. The median [IQR] BMI decreased from 31.1 [27.8, 34.9] to 30.7 [27.5, 34.5] kg/m(2). Sulfonylureas were associated with a significantly higher 12-month BMI than metformin (12-month adjusted mean difference: 1.05 kg/m(2), 95%CI: 0.90-1.20, p < 0.0001).

CONCLUSIONS

These analyses support the use of metformin as first choice of OAD because of similar glycemic control but improved BMI when compared to sulfonylureas.

The effect of incident antidiabetic regimens on lipid profiles in veterans with type 2 diabetes: a retrospective cohort

OBJECTIVE

Effects of oral antidiabetic drugs (OADs) on lipids may influence cardiovascular outcomes. Our aim was to compare time to initiation of lipid lowering medication (LLM) and 12-month lipid profiles among new OAD users.

METHODS

We identified a retrospective cohort of 17,774 veterans who received care at Veterans Administration (VA) Mid-South Network with a first OAD from 1 January 2000 to 31 December 2007. There were 6917 patients (38.9%) not on a LLM at baseline, and 3871 (56%) had complete covariates. Incident users of sulfonylurea and combination metformin + sulfonylurea were compared to metformin users for time to LLM initiation. Incident users of these OADs and thiazolidendiones were included in comparison of 12-month low-density lipoprotein (LDL), high-density lipoprotein (HDL), triglycerides (TGs), and total cholesterol. All analyses adjusted for demographics, lipids, HbA1C, healthcare utilization, and cardiovascular disease at baseline.

RESULTS

The median time to starting LLM was 2.35 years (interquartile range 0.96, 4.6) following metformin initiation and not statistically different for users of sulfonylureas, or combination OADs. Compared to metformin users, 12-month HDL was 1.35 mg/dl (95%CI: -2.01, -0.72) lower and TGs were 5.7% higher (95%CI: 1.5%, 10.0%) for sulfonylurea users; TGs were 24.8% (95%CI: 0.7%, 54.5%) higher for thiazolidinedione users. Statin users had LDL and total cholesterol 16.7 mg/dl (95%CI: -19.9, -13.5) and 18.6 mg/dl (95%CI: -22.1, -15.1) lower than non-statin users, respectively.

CONCLUSIONS

Time to LLM initiation was similar between OADs. Metformin use resulted in more favorable lipids at 12 months compared to sulfonylureas or thiazolidinediones.

Definition of patients treated with evidence based drugs in absence of prescribed daily doses: the example of acute myocardial infarction

PURPOSE

Define patients treated with evidence-based drugs in a cohort discharged after acute myocardial infarction (AMI) in absence of prescribed daily doses (PDD). To compare different drug use measures and analyze their impact on the effect estimate of risk factors related to drug use.

METHODS

AMI patients discharged in Rome during 2006-2007 were selected from the Hospital Information System. Drugs claimed during the 12 months after discharge were retrieved. Measures of drug use were defined as: 'continuity' (one prescription each follow-up quarter-year) and the 'proportion of days covered' calculated by defined daily doses (DDDs) or pill counts (PCs) (≥ 80% of individual follow-up). Poly-therapy was defined through the same drug use measure for all drug groups. Kappa index was calculated to analyze the concordance between measures. For each measure we estimated the effect of age, gender and Percutaneous Transluminal Coronary Angioplasty (PTCA) on poly-therapy.

RESULTS

Poly-therapy rates varied between 11.5 and 37.8% in the cohort and between 17.3 and 56.9% in patients with at least one prescription for all drugs. Concordance between all measures was high for antiplatelets (k=0.74) and very low for beta-blockers (k=0.22). According to measures used, gender and older age effects slightly varied, while PTCA remained a strong determinant of drug use.

CONCLUSIONS

Different measures of exposure to drug treatment may affect the estimate of the proportion of treated patients and the effect estimates of risk factors. Drug dispense registries are useful, but it is necessary to develop and validate methodologies in absence of PDD.

An efficient paradigm for genetic epidemiology cohort creation

Development of novel methodologies to efficiently create large genetic epidemiology cohorts is needed. Here we describe a rapid, precise and cost-efficient method for collection of DNA from cases previously experiencing an osteoporotic fracture by identifying cases using and administrative health-care databases. Over the course of 14 months we collected DNA from 1,130 women experiencing an osteoporotic fracture, at a cost of $54 per sample. This cohort is among the larger DNA osteoporotic fracture collections in the world. The novel method described addresses a major unmet health care research need and is widely applicable to any disease that can be identified accurately through administrative data.

Persistence with cholinesterase inhibitor therapy in a population-based cohort of patients with Alzheimer's disease

PURPOSE

To estimate the risk (and determinants) of discontinuing cholinesterase inhibitors (ChEIs) in a population-based sample of Alzheimer's disease (AD) patients.

METHODS

This is a retrospective cohort study based on linked de-identified administrative health data from the province of Saskatchewan, Canada. The cohort included all AD patients receiving a ChEI prescription during the first year of provincial coverage (2000-2001). Persistence was defined as no gap of 60+ days between depletion and subsequent refill of a ChEI prescription. Kaplan-Meier analysis was used to estimate the risk of discontinuation over 40 months. Cox regression with time-varying covariates was used to assess risk factors for ChEI discontinuation.

RESULTS

The sample included 1080 patients (64% female, average age 80 +/- 7 years). Baseline mean (SD) Mini-Mental State Examination (MMSE) and Functional Activities Questionnaire (FAQ) scores were 20.8 (4.4) and 17.5 (7.7), respectively. Over 40 months, 84% discontinued therapy. The 1-year risk of discontinuation was 66.4% (95%CI 63.5-69.3%). Discontinuation was significantly more likely for females (adjusted HR 1.34, 95%CI 1.16-1.55) and among those with lower MMSE scores (2.52, 2.01-3.17 if <15), not receiving social assistance (1.25, 1.07-1.45), and paying at least 65% of total prescription costs (1.51, 1.30-1.74). It was significantly less likely for patients with frequent physician visits (0.78, 0.66-0.93, for 7-19 vs. <7 visits), higher Chronic Disease Scores (0.74, 0.61-0.89, for 7+ vs. <4), and FAQ scores of 9+ (0.82, 0.69-0.99).

CONCLUSION

The likelihood of discontinuing ChEI therapy was high in this real-world sample of AD patients. Significant predictors included clinical, socioeconomic, and practice factors.

Early discontinuation and non-adherence to adjuvant hormonal therapy are associated with increased mortality in women with breast cancer

Despite the benefit of adjuvant hormonal therapy (HT) on mortality among women with breast cancer (BC), many women are non-adherent with its use. We investigated the effects of early discontinuation and non-adherence to HT on mortality in women enrolled in Kaiser Permanente of Northern California (KPNC). We identified women diagnosed with hormone-sensitive stage I-III BC, 1996-2007, and used automated pharmacy records to identify prescriptions and dates of refill. We categorized patients as having discontinued HT early if 180 days elapsed from the prior prescription. For those who continued, we categorized patients as adherent if the medication possession ratio was ≥80%. We used Cox proportional hazards models to estimate the association between discontinuation and non-adherence with all-cause mortality. Among 8,769 women who filled at least one prescription for HT, 2,761 (31%) discontinued therapy. Of those who continued HT, 1,684 (28%) were non-adherent. During a median follow-up of 4.4 years, 813 women died. Estimated survival at 10 years was 80.7% for women who continued HT versus 73.6% for those who discontinued (P < 0.001). Of those who continued, survival at 10 years was 81.7 and 77.8% in women who adhered and non-adhered, respectively (P < 0.001). Adjusting for clinical and demographic variables, both early discontinuation (HR 1.26, 95% CI 1.09-1.46) and non-adherence (HR 1.49, 95% CI 1.23-1.81), among those who continued, were independent predictors of mortality. Both early discontinuation and non-adherence to HT were common and associated with increased mortality. Interventions to improve continuation of and adherence to HT may be critical to improve BC survival.

Methods to examine the impact of compliance to osteoporosis pharmacotherapy on fracture risk: systematic review and recommendations

The objective of this study was to review the methods of prior studies that estimate the association between compliance to osteoporosis pharmacotherapy on fracture risk, and make recommendations to guide future research. We completed a systematic search of MEDLINE to identify all English language nonexperimental studies that examined the impact of adherence to osteoporosis pharmacotherapy on fracture risk. Studies that measured compliance were eligible and those that only examined persistence were excluded. We summarized the methodology of each study and make recommendations for future research. We identified 14 eligible articles: nine cohort and five nested case-control. Length of baseline (lookback) periods ranged between 3 months and 2 years, with nearly all studies (86%) restricting inclusion to treatment-naïve users. A threshold of 80% was most commonly used to define compliance (n = 10), with few studies providing a more thorough analysis through categorical (n = 3) or continuous (n = 1) measures. All nine cohort studies adjusted for age, sex, prior fracture, and at least one other comorbidity or drug; two cohort studies adjusted for a comorbidity score. Two of the five case-control studies clearly controlled for age, sex, drug exposure, event date and length of follow up. One study considered a theoretical sensitivity analysis to account for potential healthy adherer bias, yet all mentioned limitations related to possible residual confounding. We identify great variability in methods of prior studies that evaluate the impact of compliance to osteoporosis pharmacotherapy on fracture risk, and make recommendations to guide future research.

Influence of caregiver and provider communication on symptom days and medication use for inner-city children with asthma

BACKGROUND

Effective pediatric guideline-based asthma care requires the caregiver to accurately relay the child's symptom frequency, pattern of rescue and controller medication use, and level of asthma control to the child's primary care clinician.

OBJECTIVE

This study evaluated the longitudinal effects of a caregiver-clinician asthma communication education intervention (ACE) relative to an asthma education control group (CON) on symptom days and controller medication use in inner-city children with asthma.

PARTICIPANTS AND METHODS

231 inner-city children with asthma, recruited from urban pediatric emergency departments (EDs) and community practices, were followed for 12 months. Data included number of symptom days and nights, ED visits, hospitalizations, presence of limited activity, and controller medication use over 12 months. Pharmacy records were used to calculate controller to total asthma medication ratios as a proxy of appropriate controller medication use. Multivariate logistic regression models were used to identify factors associated with number of symptom days and nights over the past 30 days at the 12-month follow-up.

RESULTS

Most caregivers rated the communication with their child's clinician as high. Unadjusted and adjusted rates of symptom days and nights did not differ by group at follow-up. ACE children tended towards a higher controller to total medication ratio at 12 months as compared to CON children (mean ratio: ACE: 0.54, SD 0.3; CON, 0.45, SD 0.4; p = .07). Activity limitation due to asthma and persistent asthma severity were the only factors significantly associated with reporting any symptom day within the past 30 days, adjusting for treatment group, number of oral corticosteroid courses and number of clinician visits in the last 6 months, seasonality, insurance type, and controller to total asthma medication ratio covariates.

CONCLUSION

A home-based caregiver asthma communication educational intervention was not associated with decreased symptom days. However, a trend was noted in higher controller to total medication ratios in the intervention group. Inner-city caregivers of children with asthma may require a health systems approach to help convey the child's asthma health information to their clinician.

Early discontinuation and nonadherence to adjuvant hormonal therapy in a cohort of 8,769 early-stage breast cancer patients

PURPOSE

While studies have found that adjuvant hormonal therapy for hormone-sensitive breast cancer (BC) dramatically reduces recurrence and mortality, adherence to medications is suboptimal. We investigated the rates and predictors of early discontinuation and nonadherence to hormonal therapy in patients enrolled in Kaiser Permanente of Northern California health system.

PATIENTS AND METHODS

We identified women diagnosed with hormone-sensitive stage I-III BC from 1996 to 2007 and used automated pharmacy records to identify hormonal therapy prescriptions and dates of refill. We used Cox proportional hazards regression models to analyze factors associated with early discontinuation and nonadherence (medication possession ratio < 80%) of hormonal therapy.

RESULTS

We identified 8,769 patients with BC who met our eligibility criteria and who filled at least one prescription for tamoxifen (43%), aromatase inhibitors (26%), or both (30%) within 1 year of diagnosis. Younger or older age, lumpectomy (v mastectomy), and comorbidities were associated with earlier discontinuation, while Asian race, being married, earlier year at diagnosis, receipt of chemotherapy or radiotherapy, and longer prescription refill interval were associated with completion of 4.5 years of therapy. Of those who continued therapy, similar factors were associated with full adherence. Women age younger than 40 years had the highest risk of discontinuation (hazard ratio, 1.51; 95% CI, 1.23 to 1.85). By 4.5 years, 32% discontinued therapy, and of those who continued, 72% were fully adherent.

CONCLUSION

Only 49% of patients with BC took adjuvant hormonal therapy for the full duration at the optimal schedule. Younger women are at high risk of nonadherence. Interventions to improve adherence and continuation of hormonal therapy are needed, especially for younger women.

Immunosuppressant therapy adherence and graft failure among pediatric renal transplant recipients

The study objective was to determine the association between immunosuppressant therapy (IST) adherence and graft failure among pediatric renal transplant recipients (RTRs) using data reported in the United States Renal Data System (USRDS), which contains Medicare prescription claims. RTRs (<or=18 years) who received their only transplant during 1995-2000, experienced graft survival more than 6 months posttransplant, had 36 months of USRDS data (or had data until graft failure or death), utilized Medicare IST coverage, and were prescribed cyclosporine/tacrolimus were included. IST adherence was measured by medication possession ratio (MPR). Cox proportional hazards analysis was used to assess the relationship between time to graft failure and continuous MPR. MPR quartiles were used to examine MPR as a categorical variable (Quartile 4 = adherent group, Quartiles 1-3 = nonadherent group). Kaplan-Meier estimates of time to graft failure were compared between adherent and nonadherent groups. 877 RTRs met inclusion criteria. Cox proportional hazards modeling suggested that greater adherence was significantly associated with longer time to graft failure (p = 0.009), after adjusting for relevant clinical factors. Kaplan-Meier analysis found a difference between adherent and nonadherent groups in graft survival by time (chi(2)= 5.68, p = 0.017). Interventions promoting adherence should be implemented among pediatric RTRs and parents/guardians to optimize graft survival.

First-year treatment adherence among outpatients initiating antihypertensive medication in Korea: results of a retrospective claims review

BACKGROUND

Patients' adherence to antihypertensive drug therapy-especially at the beginning of treatment-is essential for preventing serious cardiovascular complications over the long term.

OBJECTIVES

This study was conducted to assess adherence among hypertensive patients who initiated antihypertensive pharmacotherapy and to identify whether it was related to the medical provider, dispensing patterns, or comorbidities.

METHODS

We reviewed the computerized claim records submitted to Korea's Health Insurance Review Agency (which maintains data for all medication prescriptions for Korean residents) between July 2004 and December 2006. We processed the claims of adult hypertensive patients who initiated therapy with an antihypertensive medication in 2005. Medication adherence was assessed by the cumulative medication adherence (CMA), calculated by dividing the sum of a day's supply (obtained over a series of intervals) by the total number of days in the time period. Good adherence was defined as CMA > or =80%.

RESULTS

The records of 725,220 antihypertensive patients aged > or =20 years were included in the analysis. The mean CMA value of the study group was 59.6% (median, 67.6%), and 39.2% of the patients had good adherence (CMA > or =80%). In multiple logistic regression analysis, the likelihood of a good adherence rate was greater when the medical provider was from a public health center (adjusted odds ratio [AOR], 2.71) or private clinic (AOR, 1.99) than a general hospital (ie, a hospital with >100 beds and > or =9 major departments) (AOR, 1.00). The likelihood of good adherence was greater when the medical provider's specialty was internal medicine (AOR, 1.00) versus family medicine (AOR, 0.96) or another specialty (AOR, 0.85). The odds of good adherence were greater among patients prescribed an angiotensin-converting enzyme inhibitor or angiotensin II receptor blocker (AOR, 1.00) or combined drugs without a diuretic (AOR, 1.01) as the first-line drug rather than other drugs (AOR, < or =0.92). The likelihood of good adherence was also better when the mean daily number of antihypertensive pills was >1 to 2 (AOR, 1.22) or >2 to 3 (AOR, 1.34) than when it was < or =1 (AOR, 1.00). The likelihood of good adherence was lower among patients without target organ disease or metabolic syndrome (AOR, 1.00) and highest among those with > or =4 relevant comorbidities (AOR, 1.85).

CONCLUSIONS

The overall CMA of these hypertensive Korean patients who started antihypertensive therapy for the first time was <60%, and the rate of good adherence (CMA > or =80%) was <40%. Good medication adherence appeared to be related to the type of medical provider who prescribed the medication, the type of antihypertensive agent prescribed, the number of agents used, and the number of related comorbidities that a patient had.

Costs of medication nonadherence in patients with diabetes mellitus: a systematic review and critical analysis of the literature

OBJECTIVES

Information on the health care costs associated with nonadherence to treatments for diabetes is both limited and inconsistent. We reviewed and critically appraised the literature to identify the main methodological issues that might explain differences among reports in the relationship of nonadherence and costs in patients with diabetes.

METHODS

Two investigators reviewed Medline, EMBASE, Cochrane library and CINAHL and studies with information on costs by level of adherence in patients with diabetes published between January 1, 1997 and September 30th 2007 were included.

RESULTS

A total of 209 studies were identified and ten fulfilled the inclusion criteria. All included studies analyzed claims data and 70% were based on non-Medicaid and non-Medicare databases. Low medication possession ratios were associated with higher costs. Important differences were found in the ICD-9/ICD-9 CM codes used to identify patients and their diagnoses, data sources, analytic window period, definitions of adherence measures, skewness in cost data and associated statistical issues, adjustment of costs for inflation, adjustment for confounders, clinical outcomes and costs.

CONCLUSIONS

Important variation among cost estimates was evident, even within studies of the same population. Readers should be cautious when comparing estimated coefficients from various studies because methodological issues might explain differences in the results of costs of nonadherence in diabetes. This is particularly important when estimates are used as inputs to pharmacoeconomic models.

Prospective validation of eight different adherence measures for use with administrative claims data among patients with schizophrenia

OBJECTIVE

The aim of this study was to compare the predictive validity of eight different adherence measures by studying the variability explained between each measure and hospitalization episodes among Medicaid-eligible persons diagnosed with schizophrenia on antipsychotic monotherapy.

METHODS

This study was a retrospective analysis of the Arkansas Medicaid administrative claims data. Continuously eligible adult schizophrenia (ICD-9-CM = 295.**) patients on antipsychotic monotherapy were identified in the recruitment period from July 2000 through April 2004. Adherence rates to antipsychotic therapy in year 1 were calculated using eight different measures identified from the literature. Univariate and multivariable logistic regression models were used to prospectively predict all-cause and mental health-related hospitalizations in the follow-up year.

RESULTS

Adherence rates were computed for 3395 schizophrenic patients with a mean age of 42.9 years, of which 52.5% (n = 1782) were females, and 52.8% (n = 1793) were white. The proportion of days covered (PDC) and continuous measure of medication gaps measures of adherence had equal C-statistics of 0.571 in predicting both all-cause and mental health-related hospitalizations. The medication possession ratio (MPR) continuous multiple interval measure of oversupply were the second best measures with equal C-statistics of 0.568 and 0.567 for any-cause and mental health-related hospitalizations. The multivariate adjusted models had higher C-statistics but provided the same rank order results.

CONCLUSIONS

MPR and PDC were among the best predictors of any-cause and mental health-related hospitalization, and are recommended as the preferred adherence measures when a single measure is sought for use with administrative claims data for patients not on polypharmacy.

Good and poor adherence: optimal cut-point for adherence measures using administrative claims data

OBJECTIVE

To identify the adherence value cut-off point that optimally stratifies good versus poor compliers using administratively derived adherence measures, the medication possession ratio (MPR) and the proportion of days covered (PDC) using hospitalization episode as the primary outcome among Medicaid eligible persons diagnosed with schizophrenia, diabetes, hypertension, congestive heart failure (CHF), or hyperlipidemia.

RESEARCH DESIGN AND METHODS

This was a retrospective analysis of Arkansas Medicaid administrative claims data. Patients > or =18 years old had to have at least one ICD-9-CM code for the study diseases during the recruitment period July 2000 through April 2004 and be continuously eligible for 6 months prior and 24 months after their first prescription for the target condition. Adherence rates to disease-specific drug therapy were assessed during 1 year using MPR and PDC. MAIN OUTCOME MEASURE AND ANALYSIS SCHEME: The primary outcome measure was any-cause and disease-related hospitalization. Univariate logistic regression models were used to predict hospitalizations. The optimum adherence value was based on the adherence value that corresponded to the upper most left point of the ROC curve corresponding to the maximum specificity and sensitivity.

RESULTS

The optimal cut-off adherence value for the MPR and PDC in predicting any-cause hospitalization varied between 0.63 and 0.89 across the five cohorts. In predicting disease-specific hospitalization across the five cohorts, the optimal cut-off adherence values ranged from 0.58 to 0.85.

CONCLUSIONS

This study provided an initial empirical basis for selecting 0.80 as a reasonable cut-off point that stratifies adherent and non-adherent patients based on predicting subsequent hospitalization across several highly prevalent chronic diseases. This cut-off point has been widely used in previous research and our findings suggest that it may be valid in these conditions; it is based on a single outcome measure, and additional research using these methods to identify adherence thresholds using other outcome metrics such as laboratory or physiologic measures, which may be more strongly related to adherence, is warranted.

Barriers to and determinants of medication adherence in hypertension management: perspective of the cohort study of medication adherence among older adults

Low adherence to antihypertensive medication remains a public health challenge. Understanding barriers to, and determinants of, adherence to antihypertensive medication may help identify interventions to increase adherence and improve outcomes. The Cohort Study of Medication Adherence in Older Adults is designed to assess risk factors for low antihypertensive medication adherence, explore differences across age, gender, and race subgroups, and determine the relationship of adherence with blood pressure control and cardiovascular outcomes over time. This article discusses the relevance of this study in addressing the issue of barriers to anithypertensive medication adherence.

An empirical basis for standardizing adherence measures derived from administrative claims data among diabetic patients

OBJECTIVE

To compare the predictive validity of 8 different adherence measures by studying the variability explained between each measure and 2 outcome measures: hospitalization episodes and total nonpharmacy cost among Medicaid eligible persons diagnosed with diabetes.

RESEARCH DESIGN

This study was a retrospective analysis of the Arkansas Medicaid administrative claims data from January 2000 to December 2006.

SUBJECTS

Diabetic (ICD-9-CM = 250.0 x - 250.9 x, where x = 0 or 2) patients were identified in the recruitment period July 2000 through April 2004. Patients had to be >or=18 years old and have at least 2 prescription fills in the index period for an oral antidiabetic drug.

MEASURES

: Adherence rates to oral antidiabetic therapy were contrasted using the following 8 measures; including the medication possession ratio (MPR), proportion of days covered (PDC), refill compliance rate (RCR), compliance ratio (CR), medication possession ratio, modified (MPRm), continuous measure of medication gaps (CMG), and continuous multiple interval measure of oversupply (CMOS and continuous, single interval measure of medication acquisition (CSA). Multivariate and univariate linear and logistic regression models were used to prospectively predict nonpharmacy costs and hospitalizations in the follow-up year.

RESULTS

A total of 4943 diabetic patients were studied. In predicting any cause hospitalization, univariate models with PDC and CMG had the highest predictive validity (C-statistic: 0.544). Multivariate models with MPR, PDC, CMG or continuous multiple interval measure of oversupply (CMOS) as adherence measures had the highest C-statistics of 0.701 in predicting diabetes specific hospitalizations. None of the adherence measures were significantly associated with nonpharmacy cost.

CONCLUSIONS

MPR and PDC had the highest predictive validity for hospitalization episodes. These 2 measures should be considered first when selecting among adherence measures when using administrative prescription claims data.

Seasonal patterns of controller and rescue medication dispensed in underserved children with asthma

OBJECTIVE

To determine whether temporal trends exist for short-acting beta agonist (SABA), oral corticosteroid (OCS), and anti-inflammatory prescription fills in children with persistent asthma.

METHOD

This was a longitudinal analysis of pharmacy record data and health information data obtained by parent report over 12 months for children with persistent asthma 2 to 9 years of age. Eligible children had to report current nebulizer use and one or more emergency department visits or hospitalizations within the past 12 months.

RESULTS

Children were primarily African-American (89%), male (64%), received Medicaid health insurance (82%), and were a mean age of 4.5 years (SD 2.1). Few families (11%) reported any problems paying for their child's asthma medications at baseline or at the 12-month follow-up. There was a high degree of association between filling a rescue (SABA or OCS) and controller (leukotriene modifier, inhaled corticosteroid, cromolyn) medication during the same month for all months with Pearson's correlation coefficients ranging from a low of 0.28 for October to a high of 0.53 in September. Short-acting beta agonist fills were significantly more likely to be filled concurrently with inhaled corticosteroid fills. However, significantly fewer prescription fills were obtained in the summer months with an acceleration of medication fills in September through December and an increase in early spring.

CONCLUSIONS

There was a summer decline in both inhaled corticosteroid and SABA fills. Timing of asthma monitoring visits to occur before peak prescription fill months, i.e., August and December for an asthma "tune-up," theoretically could improve asthma control. During these primary care visits children could benefit from more intensive monitoring of medication use including monitoring lung function, frequency of prescription refills, and assessment of medication device technique to ensure that an effective dose of medication is adequately delivered to the respiratory tract. Additionally, scheduling non-urgent asthma care visits at pre-peak prescription fill months can take advantage of "step down" during decreased symptom periods and when appropriate restart daily controller medications to "step up" prior to peak asthma periods.

Duration of antipsychotic drug therapy in real-world practice: a comparison with CATIE trial results

BACKGROUND

Duration of drug therapy is a key measure of drug effectiveness in schizophrenia. The Clinical Antipsychotic Trials of Intervention Effectiveness (CATIE) trial found that only olanzapine achieved a longer time to all-cause-discontinuation (TTAD) than a standard therapy comparator. This study compares the TTAD achieved when using alternative antipsychotics to treat patients with schizophrenia in real-world practice settings.

METHODS

A total of 219,504 episodes of antipsychotic therapy initiated in the years 2000 to 2002 were identified using data from the California Medicaid (Medi-Cal) program. To capture the full range of treatment scenarios facing clinicians, four episode types were included: restarting therapy using the drug used in the preceding episode; restarting therapy using a different medication (delayed switches); switching therapy without a break in therapy; and augmentation. TTAD and changes in therapy were analyzed using ordinary least squares and logistic regressions and Cox proportional hazards models.

RESULTS

Atypical antipsychotics consistently achieved longer TTAD and reduced switching rates relative to conventional antipsychotics. Differences in TTAD favoring atypical antipsychotics were 13 to 15 days in restart episodes; 28 to 36 days for delayed switching episodes; 41 to 52 days in switching episodes; and 59 to 63 days for augmentation (P < 0.0001 for all estimates). Differences between the atypical antipsychotics were smaller than reported in other studies and may not be clinically significant.

CONCLUSIONS

This study confirms two results from the CATIE study: Patients with schizophrenia frequently do not achieve stable, long-term drug therapy regardless of the specific drug used, and olanzapine achieved longer TTAD than conventional drugs. However, this study also found that patients treated with risperidone and quetiapine also achieved longer TTAD than patients treated with conventional antipsychotics.

Long-term adherence to evidence based secondary prevention therapies after acute myocardial infarction

BACKGROUND

After acute myocardial infarction (AMI), treatment with beta-blockers and angiotensin-converting enzyme inhibitors (ACEI) is widely recognized as crucial to reduce risk of a subsequent AMI. However, many patients fail to consistently remain on these treatments over time, and long-term adherence has not been well described.

OBJECTIVE

To examine the duration of treatment with beta-blockers and ACEI within the 24 months after an AMI.

DESIGN

A retrospective, observational study using medical and pharmacy claims from a large health plan operating in the Northeastern United States.

SUBJECTS

Enrollees with an inpatient claim for AMI who initiated beta-blocker (N = 499) or ACEI (N = 526) therapy.

MEASUREMENT

Time from initiation to discontinuation was measured with pharmacy refill records. Associations between therapy discontinuation and potential predictors were estimated using a Cox proportional hazards model.

RESULTS

ACEI discontinuation rates were high: 7% stopped within 1 month, 22% at 6 months, 32% at 1 year and 50% at 2 years. Overall discontinuation rates for beta-blockers were similar, but predictors of discontinuation differed for the two treatment types. For beta-blockers, the risk of discontinuation was highest among males and those from low-income neighborhoods; patients with comorbid hypertension and peripheral vascular disease were less likely to discontinue therapy. These factors were not associated with ACEI discontinuation.

CONCLUSION

Many patients initiating evidence-based secondary prevention therapies after an AMI fail to consistently remain on these treatments. Adherence is a priority area for development of better-quality measures and quality-improvement interventions. Barriers to beta-blocker adherence for low-income populations need particular attention.

Studying prescription drug use and outcomes with medicaid claims data: strengths, limitations, and strategies

Medicaid claims and eligibility data, particularly when linked to other sources of patient-level and contextual information, represent a powerful and under-used resource for health services research on the use and outcomes of prescription drugs. However, their effective use poses many methodological and inferential challenges. This article reviews strengths, limitations, challenges, and recommended strategies in using Medicaid data for research on the initiation, continuation, and outcomes of prescription drug therapies. Drawing from published research using Medicaid data by the investigators and other groups, we review several key validity and methodological issues. We discuss strategies for claims-based identification of diagnostic subgroups and procedures, measuring and modeling initiation and persistence of regimens, analysis of treatment disparities, and examination of comorbidity patterns. Based on this review, we discuss "best practices" for appropriate data use and validity checking, approaches to statistical modeling of longitudinal patterns in the presence of typical challenges, and strategies for strengthening the power and potential of Medicaid datasets. Finally, we discuss policy implications, including the potential for the research use of Medicare Part D data and the need for further initiatives to systematically develop and optimally use research datasets that link Medicaid and other sources of clinical and outcome information.

Antihypertensive drug medication adherence and its affecting factors in South Korea

CONTEXT

Uncontrolled hypertension attributable to low medication adherence may cause such serious complications as cardiovascular disease and stroke.

OBJECTIVES

To estimate adherence to antihypertensive drug medication of the nation's representative sample in South Korea and to identify factors affecting medication adherence.

DATA SOURCES

We obtained claims data and qualification data of compulsory from the National Health Insurance, which covers almost all Korean, and identified those who got a prescription of antihypertensives during calendar year 2004.

PATIENTS

A total of 2,455,193 patients were included as study subjects. Cumulative medication adherence (CMA) was used as an index of medication adherence. Above 80% of CMA was defined as appropriate medication adherence.

RESULTS

Average CMA in the total of 2,455,193 patients was 81.4%. Appropriate adherence (CMA >or=80%) rate was 54.7% and those whose CMA is below 50% occupied 17.9%. In multiple logistic regression analysis, probability of appropriate medication adherence decreased in female gender, as age decreased, when patients have disability, when patients' residential area were from metropolitan city to city (OR: 0.91-0.92), to rural area (OR: 0.76-0.78), to extreme rural area (OR: 0.72-0.74), prescription days per visit decreased, and the number of prescribing physicians increased.

CONCLUSIONS

Identifying these factors in a target population or community, followed by developing intervention programs to increase antihypertensive medication adherence is needed. Also, medication adherence rate produced in this study can be used as a national health index and performance indexes of various hypertension control programs.

Compliance with refilling prescriptions for atypical antipsychotic agents and its association with the risks for hospitalization, suicide, and death in patients with schizophrenia in Quebec and Saskatchewan: a retrospective database study

OBJECTIVE

The objective of this analysis was to describe the patterns of compliance with atypical antipsychotics among patients with schizophrenia in actual practice in 2 Canadian provinces and to examine the relation between degrees of compliance and the risks of hospitalization, suicide, and death.

METHODS

Adults with a diagnosis of schizophrenia who filled at least 1 prescription for risperidone, olanzapine, or quetiapine were identified in the Quebec public prescription drug insurance plan database (from July 1, 2001, to December 31, 2004) and the Saskatchewan Health database (from January 1, 1999, to December 31, 2003). Compliance was assessed based on the medication possession ratio, which was estimated as the proportion of days for which medication was available over each month of follow-up (> or = 80% = good compliance; 50%-79% = moderate compliance; < 50% = poor compliance). The association between the early and long-term effects of compliance and the risks of hospitalization, suicide, and death were examined using Cox regression, with adjustment for baseline age, sex, and use of antidepressants, sedatives, and lithium (Quebec only).

RESULTS

respective 41,754 and 3291 patients were identified from the Quebec and Saskatchewan databases. Approximately half of the patients in each cohort were male and were aged < 45 years. Many patients had good compliance over the full follow-up period (Quebec, 61%; Saskatchewan, 45%); however, poor compliance was seen in 23% of patients from Quebec and 34% of those from Saskatchewan. Compared with poor compliance, the long-term effect of good compliance was associated with a significantly decreased risk of all-cause hospitalization (Quebec: adjusted hazard ratio [HR] = 0.60; 95% CI, 0.57-0.64; Saskatchewan: adjusted HR = 0.81; 95% CI, 0.69-0.95) and psychosis-related hospitalization (Quebec: adjusted HR = 0.37; 95% Cl, 0.34-0.40; Saskatchewan: adjusted HR = 0.45; 95% CI, 0.32-0.64). The Quebec data also indicated a significant association between good versus poor compliance and a decreased risk of death (adjusted HR = 0.58; 95% CI, 0.51-0.66) and suicide (adjusted HR = 0.68; 95% CI, 0.55-0.84) that was not observed in Saskatchewan.

CONCLUSION

In this retrospective analysis of patients with schizophrenia in Quebec and Saskatchewan, good compliance with atypical antipsychotic medications was associated with substantial reductions in the risk for all-cause and psychosis-related hospitalizations.

Antihypertensive Drug Medication Adherence of People with Disabilities and its Affecting Factors in Korea

OBJECTIVES

The aims of this study were to estimate the antihypertensive medication adherence in people with a disability and a history of taking antihypertensive medication, and to identify the factors affecting medication adherence.

METHODS

The National Health Insurance claims data were linked with the National Disability Registry. People with a disability, who received a prescription of antihypertensives, were identified from a total of 85,098 cases. Cumulative medication adherence (CMA) was used as an indicator of medication adherence. A CMA>80% was defined as appropriate medication adherence. Multiple logistic regression analysis was used to identify the factors affecting medication adherence.

RESULTS

The average CMA in a total of 85,098 patients was 79.5%. The appropriate adherence (CMA>or=80%) rate was 54.5% and 20.5% of patients had a CMA<50%. Multiple logistic regression analysis revealed that the probability of appropriate adherence decreased with decreasing number of prescription days per visit, increasing number of providers, the patients' residential area moving from urban to rural areas, and when patients have an internal organ disability, auditory impairment, mobility impairment.

CONCLUSIONS

The adherence to antihypertensive medication in people with a disability is influenced by various socio-economic, clinical and regional factors. In particular, the disabled who have locomotive and communication disabilities and internal organ impairments have a higher probability of under-adherence to antihypertensive medication adherence in Korea.

Patterns of inhaled antiinflammatory medication use in young underserved children with asthma

BACKGROUND

Asthma guidelines advocate inhaled corticosteroids as the cornerstone treatment of persistent asthma, yet several studies report underuse of inhaled corticosteroids in children with persistent asthma. Moreover, few studies use objective pharmacy data as a measure of drug availability of asthma medications. We examined factors associated with the use of inhaled corticosteroids in young underserved children with persistent asthma using pharmacy records as their source of asthma medications.

METHODS

This was a cross-sectional analysis of questionnaire and pharmacy record data over a 12-month period from participants enrolled in a randomized clinical trial of a nebulizer educational intervention.

RESULTS

Although exposure to > or = 1 inhaled corticosteroids refill was high at 72%, 1 of 5 children with persistent asthma had either no medication or only short-acting beta agonist fills for 12 months. Only 20% of children obtained > or = 6 inhaled corticosteroids fills over 12 months. Obtaining > or = 3 inhaled corticosteroids fills over 12 months was significantly associated with an increase in short-acting beta agonist fills and receiving specialty care in the regression models while controlling for child age, asthma severity, number of emergency department visits, having an asthma action plan, and seeking preventive care for the child's asthma.

CONCLUSIONS

Overreliance on short-acting beta agonist and underuse of inhaled corticosteroid medications was common in this group of young children with persistent asthma. Only one fifth of children obtained sufficient controller medication fills.