Comparisons of persistence and durability among three oral antidiabetic therapies using electronic prescription-fill data: the impact of adherence requirements and stockpiling

Adherence and persistence to pharmacotherapy in patients with heart failure: a nationwide cohort study, 2014-2020

AIMS

We aimed to study initiation, adherence, and long-term persistence to beta-blockers (BB), renin-angiotensin system inhibitors (RASi), and mineralocorticoid receptor antagonists (MRA) in a nationwide cohort of patients with heart failure (HF).

METHODS

Patients aged 18-80 years in Norway with a first diagnosis of HF from 2014 until 2020 that survived ≥30 days were identified from the Norwegian Patient Registry and linked to the Norwegian Prescription Database. We collected information about BB, RASi [angiotensin-converting enzyme (ACE) inhibitors, angiotensin II receptor blockers (ARB), and angiotensin receptor-neprilysin inhibitors (ARNI)], and MRA. Dual HF therapy was defined as taking at least two out of three drug classes, whereas triple HF therapy was defined as taking all three. Initiation (time to initiation) and persistence (time to discontinuation using a grace period of 30 days) of HF drugs was calculated by the Kaplan-Meier method, followed to outcome of interest, death, or December 2020. One-year adherence was measured as proportion of days covered (PDC) using a cut-off at 80%. For adherence and persistence measurements, we allowed for maximum 60 days of stockpiling and switching within drug groups. We performed sensitivity analyses to test the robustness of our findings.

RESULTS

Out of 54 899 patients included in the cohort, 75%, 69%, and 21% initiated a BB, RASi, and MRA, respectively, whereas 13% did not receive any. Dual and triple HF therapy was prescribed to 61% and 16%, respectively. The proportion of adherent patients during the first year following initiation was 83%, 81%, 84%, and 61% for BB, RASi, ARNI, and MRA, whereas 42% and 5% were adherent to dual and triple HF therapy, respectively. From 2 to 5 years following initiation, persistence decreased from 58% to 38%, 57% to 37%, and 31% to 15% for BB, RASi, and MRA, respectively. Within the RASi group, persistence was higher for ARNI than for ACEI and ARB. There were no major changes in either initiation or adherence of the drug classes from 2014 to 2019, except for an increase in initiation and adherence of MRA.

CONCLUSIONS

We found low adherence to dual and triple HF therapies in this nationwide cohort study of newly diagnosed HF patients. Efforts are needed to increase adherence and persistence to HF therapies into clinical practice, emphasizing maintenance of multiple drug therapies in patients with such an indication.

Time to Treatment Intensification in Patients Receiving DPP4 Inhibitors Versus Sulfonylureas as the First Add-On to Metformin Monotherapy: A Retrospective Cohort Study

Background: To verify whether, in patients on metformin (MET) monotherapy for type 2 diabetes (T2D), the add-on of a dipeptidyl peptidase inhibitor (DPP4i) compared to a sulfonylurea (SU) can delay the time to the subsequent treatment intensification (TI).

Methods: Population-based administrative data banks from four Italian geographic areas were used. Patients aged ≥18 years on MET monotherapy receiving first DPP4i or SU dispensing between 2008 and 2015 (cohort entry) were followed up to the occurrence of TI (insulin dispensing or add-on of a third non-insulin hypoglicemic >180 days after cohort entry), treatment discontinuation, switch, cancer, death, TI occurrence within, end of data availability, end of study period (31 December 2016), whichever came first. Patients on MET + DPP4i were matched 1:1 with those on MET + SU by sex, age, year of cohort entry, and data bank. Hazard Ratio (HR) and 95% confidence intervals (95%CI) were estimated using multivariable Cox regression model including matching variables and potential confounders measured at baseline. Different sensitivity analyses were performed: i) matching at 180 days after cohort entry, ii) intent to treat (ITT) analysis, iii) matching by duration of MET monotherapy, iv) matching by propensity score.

Results: The matched study cohort included 10,600 patients. Overall, 763 TI were observed (4.5/100 person-years; mean follow-up = 1.6 years). The primary analysis showed no difference in time to TI between the two groups (HR = 1.02; 95% CI = 0.88–1.19). Sensitivity analyses confirmed this result, except from the ITT analysis (HR = 1.27; 1.13–1.43).

Conclusion: The use of a DPP4i rather than a SU as add-on to MET monotherapy was not associated with a delay in treatment intensification.

Patient Factors Influencing Outpatient Retention in Patients with Affective and Anxiety Disorders: A Retrospective Study

OBJECTIVE

The aim of the present study is to identify the factors that affect retention in outpatients with psychiatric disorders as indicators of treatment adherence, including Minnesota Multiphasic Personality Inventory (MMPI) scores.

METHODS

The medical records of 146 patients diagnosed with major depressive disorder, bipolar disorder, or anxiety disorder for at least 10 years and discharged were retrospectively reviewed in the present study. The subjects were categorized based on the duration of outpatient treatment as < 6 months (L6) or ≥ 6 months (M6) groups and reclassified as < 36 months (L36) and ≥ 36 months (M36) groups. The demographic, clinical, and personality characteristics of the groups were compared.

RESULTS

Patients in M6 and M36 groups were more likely to have a higher educational level compared with those in the L6 and L36 groups, respectively. Patients in the M6 group showed significantly lower hypomania (Ma) scores on the MMPI test than did patients in the L6 group.

CONCLUSION

The association between high Ma score on the MMPI test and early discontinuation of treatment suggests that impulsivity, hostility, and disinhibition confer higher risk of nonadherence.

Hospitalization for Heart Failure Among Patients With Diabetes Mellitus and Reduced Kidney Function Treated With Metformin Versus Sulfonylureas: A Retrospective Cohort Study

Background Metformin and sulfonylurea are commonly prescribed oral medications for type 2 diabetes mellitus. The association of metformin and sulfonylureas on heart failure outcomes in patients with reduced estimated glomerular filtration rate remains poorly understood. Methods and Results This retrospective cohort combined data from National Veterans Health Administration, Medicare, Medicaid, and the National Death Index. New users of metformin or sulfonylurea who reached an estimated glomerular filtration rate of 60 mL/min per 1.73 m2 or serum creatinine of 1.5 mg/dL and continued metformin or sulfonylurea were included. The primary outcome was hospitalization for heart failure. Echocardiogram reports were obtained to determine each patient's ejection fraction (EF) (reduced EF <40%; midrange EF 40%-49%; ≥50%). The primary analysis estimated the cause-specific hazard ratios for metformin versus sulfonylurea and estimated the cumulative incidence functions for heart failure hospitalization and competing events. The weighted cohort included 24 685 metformin users and 24 805 sulfonylurea users with reduced kidney function (median age 70 years, estimated glomerular filtration rate 55.8 mL/min per 1.73 m2). The prevalence of underlying heart failure (12.1%) and cardiovascular disease (31.7%) was similar between groups. There were 16.9 (95% CI, 15.8-18.1) versus 20.7 (95% CI, 19.5-22.0) heart failure hospitalizations per 1000 person-years for metformin and sulfonylurea users, respectively, yielding a cause-specific hazard of 0.85 (95% CI, 0.78-0.93). Among heart failure hospitalizations, 44.5% did not have echocardiogram information available; 29.3% were categorized as reduced EF, 8.9% as midrange EF, and 17.2% as preserved EF. Heart failure hospitalization with reduced EF (hazard ratio, 0.79; 95% CI, 0.67-0.93) and unknown EF (hazard ratio, 0.84; 95% CI 0.74-96) were significantly lower in metformin versus sulfonylurea users. Conclusions Among patients with type 2 diabetes mellitus who developed worsening kidney function, persistent metformin compared with sulfonylurea use was associated with reduced heart failure hospitalization.

Hospitalization for Lactic Acidosis Among Patients With Reduced Kidney Function Treated With Metformin or Sulfonylureas

OBJECTIVE

To compare the risk of lactic acidosis hospitalization between patients treated with metformin versus sulfonylureas following development of reduced kidney function.

RESEARCH DESIGN AND METHODS

This retrospective cohort combined data from the National Veterans Health Administration, Medicare, Medicaid, and the National Death Index. New users of metformin or sulfonylureas were followed from development of reduced kidney function (estimated glomerular filtration rate [eGFR] <60 mL/min/1.73 m2 or serum creatinine ≥1.4 mg/dL [female] or 1.5 mg/dL [male]) through hospitalization for lactic acidosis, death, loss to follow-up, or study end. Lactic acidosis hospitalization was defined as a composite of primary discharge diagnosis or laboratory-confirmed lactic acidosis (lactic acid ≥2.5 mmol/L and either arterial blood pH <7.35 or serum bicarbonate ≤19 mmol/L within 24 h of admission). We report the cause-specific hazard of lactic acidosis hospitalization between metformin and sulfonylureas from a propensity score-matched weighted cohort and conduct an additional competing risks analysis to account for treatment change and death.

RESULTS

The weighted cohort included 24,542 metformin users and 24,662 sulfonylurea users who developed reduced kidney function (median age 70 years, median eGFR 55.8 mL/min/1.73 m2). There were 4.18 (95% CI 3.63, 4.81) vs. 3.69 (3.19, 4.27) lactic acidosis hospitalizations per 1,000 person-years among metformin and sulfonylurea users, respectively (adjusted hazard ratio [aHR] 1.21 [95% CI 0.99, 1.50]). Results were consistent for both primary discharge diagnosis (aHR 1.11 [0.87, 1.44]) and laboratory-confirmed lactic acidosis (1.25 [0.92, 1.70]).

CONCLUSIONS

Among veterans with diabetes who developed reduced kidney function, occurrence of lactic acidosis hospitalization was uncommon and not statistically different between patients who continued metformin and those patients who continued sulfonylureas.

Prevalence and Risk Factors for Opioid-Induced Constipation in an Older National Veteran Cohort

Objectives

This research describes the prevalence and covariates associated with opioid-induced constipation (OIC) in an observational cohort study utilizing a national veteran cohort and integrated data from the Center for Medicare and Medicaid Services (CMS).

Methods

A cohort of 152,904 veterans with encounters between 1 January 2008 and 30 November 2010, an exposure to opioids of 30 days or more, and no exposure in the prior year was developed to establish existing conditions and medications at the start of the opioid exposure and determining outcomes through the end of exposure. OIC was identified through additions/changes in laxative prescriptions, all-cause constipation identification through diagnosis, or constipation related procedures in the presence of opioid exposure. The association of time to constipation with opioid use was analyzed using Cox proportional hazard regression adjusted for patient characteristics, concomitant medications, laboratory tests, and comorbidities.

Results

The prevalence of OIC was 12.6%. Twelve positively associated covariates were identified with the largest associations for prior constipation and prevalent laxative (any laxative that continued into the first day of opioid exposure). Among the 17 negatively associated covariates, the largest associations were for erythromycins, androgens/anabolics, and unknown race.

Conclusions

There were several novel covariates found that are seen in the all-cause chronic constipation literature but have not been reported for opioid-induced constipation. Some are modifiable covariates, particularly medication coadministration, which may assist clinicians and researchers in risk stratification efforts when initiating opioid medications. The integration of CMS data supports the robustness of the analysis and may be of interest in the elderly population warranting future examination.

Long-term comparative safety analysis of the risks associated with adding or switching to a sulfonylurea as second-line Type 2 diabetes mellitus treatment in a US veteran population

AIM

To examine the risks of all-cause mortality and cardiovascular events associated with adding vs switching to second-line therapies in a comparative safety study of people with Type 2 diabetes mellitus.

METHODS

We conducted a retrospective cohort study using an as-treated analysis of people served by the Veterans Health Administration who were on metformin and subsequently augmented this treatment or switched to other oral glucose-lowering treatments between 1998 and 2012. This study included 145 250 people with long follow-up. Confounding was addressed through several strategies, involving weighted propensity score models with rich confounder adjustment and strict inclusion criteria, coupled with an incident-user design.

RESULTS

Second-line use of sulfonylureas was related to higher mortality (hazard ratio 1.39, 95% CI 1.14, 1.70) and cardiovascular risks (hazard ratio 1.19, 95% CI 1.09, 1.30) compared with thiazolidinedione therapy. Differential hazards were associated with discontinuing or not discontinuing metformin; switching to sulfonylurea therapy was associated with a higher risk of all-cause mortality and cardiovascular events compared with all other therapies. Furthermore, add-on sulfonylurea therapy was associated with an elevated risk for both outcomes when compared with thiazolidinedione add-on therapy.

CONCLUSIONS

The results of the present study may inform decisions on whether to augment or discontinue metformin; when considering the long-term risks, switching to a sulfonylurea appears unfavourable compared with other therapies. Instead, adding a thiazolidinedione to existing metformin therapy appears to be superior to adding or switching to a sulfonylurea.

Association of Treatment With Metformin vs Sulfonylurea With Major Adverse Cardiovascular Events Among Patients With Diabetes and Reduced Kidney Function

IMPORTANCE

Before 2016, safety concerns limited metformin use in patients with kidney disease; however, the effectiveness of metformin on clinical outcomes in patients with reduced kidney function remains unknown.

OBJECTIVE

To compare major adverse cardiovascular events (MACE) among patients with diabetes and reduced kidney function who continued treatment with metformin or a sulfonylurea.

DESIGN, SETTING, AND PARTICIPANTS

Retrospective cohort study of US veterans receiving care within the national Veterans Health Administration, with data supplemented by linkage to Medicare, Medicaid, and National Death Index data from 2001 through 2016. There were 174 882 persistent new users of metformin and sulfonylureas who reached a reduced kidney function threshold (estimated glomerular filtration rate <60 mL/min/1.73 m2 or creatinine ≥1.4 mg/dL for women or ≥1.5 mg/dL for men). Patients were followed up from reduced kidney function threshold until MACE, treatment change, loss to follow-up, death, or study end (December 2016).

EXPOSURES

New users of metformin or sulfonylurea monotherapy who continued treatment with their glucose-lowering medication after reaching reduced kidney function.

MAIN OUTCOMES AND MEASURES

MACE included hospitalization for acute myocardial infarction, stroke, transient ischemic attack, or cardiovascular death. The analyses used propensity score weighting to compare the cause-specific hazard of MACE between treatments and estimate cumulative risk accounting for the competing risks of changing therapy or noncardiovascular death.

RESULTS

There were 67 749 metformin and 28 976 sulfonylurea persistent monotherapy users; the weighted cohort included 24 679 metformin and 24 799 sulfonylurea users (median age, 70 years [interquartile range {IQR}, 62.8-77.8]; 48 497 men [98%]; and 40 476 white individuals [82%], with median estimated glomerular filtration rate of 55.8 mL/min/1.73 m2 [IQR, 51.6-58.2] and hemoglobin A1c level of 6.6% [IQR, 6.1%-7.2%] at cohort entry). During follow-up (median, 1.0 year for metformin vs 1.2 years for sulfonylurea), there were 1048 MACE outcomes (23.0 per 1000 person-years) among metformin users and 1394 events (29.2 per 1000 person-years) among sulfonylurea users. The cause-specific adjusted hazard ratio of MACE for metformin was 0.80 (95% CI, 0.75-0.86) compared with sulfonylureas, yielding an adjusted rate difference of 5.8 (95% CI, 4.1-7.3) fewer events per 1000 person-years of metformin use compared with sulfonylurea use.

CONCLUSIONS AND RELEVANCE

Among patients with diabetes and reduced kidney function persisting with monotherapy, treatment with metformin, compared with a sulfonylurea, was associated with a lower risk of MACE.

Comparison of Different Strategies to Measure Medication Adherence via Claims Data in Patients With Chronic Heart Failure

Medication adherence correlates with morbidity and mortality in patients with chronic heart failure (CHF), but is difficult to assess. We conducted a retrospective methodological cohort study in 3,808 CHF patients, calculating adherence as proportion of days covered (PDC) utilizing claims data from 2010 to 2015. We aimed to compare different parameters’ influence on the PDC of elderly CHF patients exemplifying a complex chronic disease. Investigated parameters were the assumed prescribed daily dose (PDD), stockpiling, and periods of hospital stay. Thereby, we investigated a new approach using the PDD assigned to different percentiles. The different dose assumptions had the biggest influence on the PDC, with variations from 41.9% to 83.7%. Stockpiling and hospital stays increased the values slightly. These results queries that a reliable PDC can be calculated with an assumed PDD. Hence, results based on an assumed PDD have to be interpreted carefully and should be presented with sensitivity analyses to show the PDC's possible range.

Using Dispensing Data to Evaluate Adherence Implementation Rates in Community Pharmacy

Background: Medication non-adherence remains a significant problem for the health care system with clinical, humanistic and economic impact. Dispensing data is a valuable and commonly utilized measure due accessibility in electronic health data. The purpose of this study was to analyze the changes on adherence implementation rates before and after a community pharmacist intervention integrated in usual real life practice, incorporating big data analysis techniques to evaluate Proportion of Days Covered (PDC) from pharmacy dispensing data.

Methods: Retrospective observational study. A de-identified database of dispensing data from 20,335 patients (n = 11,257 on rosuvastatin, n = 6,797 on irbesartan, and n = 2,281 on desvenlafaxine) was analyzed. Included patients received a pharmacist-led medication adherence intervention and had dispensing records before and after the intervention. As a measure of adherence implementation, PDC was utilized. Analysis of the database was performed using SQL and Python.

Results: Three months after the pharmacist intervention there was an increase on average PDC from 50.2% (SD: 30.1) to 66.9% (SD: 29.9) for rosuvastatin, from 50.8% (SD: 30.3) to 68% (SD: 29.3) for irbesartan and from 47.3% (SD: 28.4) to 66.3% (SD: 27.3) for desvenlafaxine. These rates declined over 12 months to 62.1% (SD: 32.0) for rosuvastatin, to 62.4% (SD: 32.5) for irbesartan and to 58.1% (SD: 31.1) for desvenlafaxine. In terms of the proportion of adherent patients (PDC >= 80.0%) the trend was similar, increasing after the pharmacist intervention from overall 17.4 to 41.2% and decreasing after one year of analysis to 35.3%.

Conclusion: Big database analysis techniques provided results on adherence implementation over 2 years of analysis. An increase in adherence rates was observed after the pharmacist intervention, followed by a gradual decrease over time. Enhancing the current intervention using an evidence-based approach and integrating big database analysis techniques to a real-time measurement of adherence could help community pharmacies improve and sustain medication adherence.

Patterns and trends of utilization of incretin-based medicines between 2008 and 2014 in three Italian geographic areas

BACKGROUND

The incretin-based medicines GLP1 analogues (GLP1a) and dipeptidyl peptidase-4 inhibitors (DPP4i) are hypoglycaemic agents licensed for the treatment of type 2 diabetes mellitus (T2DM). Although these drugs possess comparable efficacy and low risk of hypoglycaemia, differences in terms of route of administration (subcutaneous versus oral), effect on body weight and gastrointestinal tolerabily can impact their actual use in clinical practice. This study aimed to describe the real-world utilization of incretin-based medicines in the Italian clinical practice.

METHODS

A multi-database, population-based, descriptive, cohort study was performed using administrative data collected between 2008 and 2014 from three Italian geographic areas. Subjects aged ≥18 were selected. New users were defined as those with ≥1 dispensing of GLP1a or DPP4i during the year of interest and none in the past. Trends of cumulative annual incidence of use in the general adult population were observed. New users of GLP1a or DPP4i were respectively described in terms of demographic characteristics and use of antidiabetic drugs during 1 year before and after the first incretin dispensing.

RESULTS

The overall study population included 4,943,952 subjects. A total of 7357 new users of GLP1a and 41,907 of DPP4i were identified during the study period. Incidence of use increased between 2008 (0.2‰ for both GLP1a and DPP4i) and 2011 (GLP1a = 0.6‰; DPP4i = 2.5‰) and slightly decreased thereafter. In 2014, 61% of new GLP1a users received once-daily liraglutide while 52% of new DPP4i users received metformin/DPP4i in fixed-dose. The percentage of new DPP4i users older than 65 years of age increased from 30.9 to 62.6% during the study period. Around 12% of new users had not received any antidiabetic before starting an incretin.

CONCLUSIONS

During the study period, DPP4i rapidly became the most prescribed incretin-based medicine, particularly among older new user. The choice of the specific incretin-based medicine at first prescription appeared to be directed towards those with higher convenience of use (e.g. oral DPP4i rather than subcutaneous GLP1a, once-daily liraglutide rather than twice-daily exenatide). The non-negligibile use of incretin-based medicines as first-line pharmacotherapy for T2DM warrants further effectiveness and safety evaluations to better define their place in therapy.

Real-world adherence to oral anticoagulants in atrial fibrillation patients: a study protocol for a systematic review and meta-analysis

INTRODUCTION

Atrial fibrillation (AF) is one of the leading causes of cerebrovascular mortality and morbidity. Oral anticoagulants (OACs) have been shown to reduce the incidence of cardioembolic stroke in patients with AF, adherence to treatment being an essential element for their effectiveness. Since the release of the first non-vitamin K antagonist oral anticoagulant, several observational studies have been carried out to estimate OAC adherence in the real world using pharmacy claim databases or AF registers. This systematic review aims to describe secondary adherence to OACs, to compare adherence between OACs and to analyse potential biases in OAC secondary adherence studies using databases.

METHODS AND ANALYSIS

We searched on PubMed, SCOPUS and Web of Science databases (completed in 26 September 2018) to identify longitudinal observational studies reporting days' supply adherence measures with OAC in patients with AF from refill databases or AF registers. The main study endpoint will be the percentage of patients exceeding the 80% threshold in proportion of days covered or the medication possession ratio. Two reviewers will independently screen potential studies and will extract data in a structured format. A random-effects meta-analysis will be carried out to pool study estimates. The risk of bias will be assessed using the Newcastle-Ottawa Scale for observational studies and we will also assess some study characteristics that could affect days' supply adherence estimates.

ETHICS AND DISSEMINATION

This systematic review using published aggregated data does not require ethics approval according to Spanish law and international regulations. The final results will be published in a peer-review journal and different social stakeholders, non-academic audiences and patients will be incorporated into the diffusion activities.

PROSPERO REGISTRATION NUMBER

CRD42018095646.

Estimating Adherence Based on Prescription or Dispensation Information: Impact on Thresholds and Outcomes. A Real-World Study With Atrial Fibrillation Patients Treated With Oral Anticoagulants in Spain

Objective: To estimate drug exposure, Proportion of Days Covered (PDC) and percentage of patients with PDC ≥ 80% from a cohort of atrial fibrillation patients initiating oral anticoagulant (OAC) treatment. We employed three different approaches to estimate PDC, using either data from prescription and dispensing (PD cohort) or two common designs based on dispensing information only, requiring at least one (D1) or at least two (D2) refills for inclusion in the cohorts. Finally, we assessed the impact of adherence on health outcomes according to each method. Methods: Population-based retrospective cohort of all patients with Non Valvular Atrial Fibrillation (NVAF), who were newly prescribed acenocoumarol, apixaban, dabigatran or rivaroxaban from November 2011 to December 2015 in the region of Valencia (Spain). Patients were followed for 12 months to assess adherence using three different approaches (PD, D1 and D2 cohorts). To analyze the relationship between adherence (PDC ≥ 80) defined according to each method of calculation and health outcomes (death for any cause, stroke or bleeding) Cox regression models were used. For the identification of clinical events patients were followed from the end of the adherence assessment period to the end of the available follow-up period. Results: PD cohort included all patients with an OAC prescription (n = 38,802), D1 cohort excluded fully non-adherent patients (n = 265) and D2 cohort also excluded patients without two refills separated by 180 days (n = 2,614). PDC ≥ 80% ranged from 94% in the PD cohort to 75% in the D1 cohort. Drug exposure among adherent (PDC ≥ 80%) and non-adherent (PDC < 80%) patients was different between cohorts. In adjusted analysis, high adherence was associated with a reduced risk of death [Hazard Ratio (HR): from 0.82 to 0.86] and (except in the PD cohort) the risk for ischemic stroke (HR: from 0.61 to 0.64) without increasing the risk of bleeding. Conclusion: Common approaches to assess adherence using measures based on days' supply exclude groups of non-adherent patients and, also, misattribute periods of doctors' discontinuation to patient non-adherence, misestimating adherence overall. Physician-initiated discontinuation is a major contributor to reduced OAC exposure. When using the PDC80 threshold, very different groups of patients may be classified as adherent or non-adherent depending on the method used for the calculation of days' supply measures. High adherence and high exposure to OAC treatment in NVAF patients is associated with better health outcomes.

Risk of Hypoglycemia Following Hospital Discharge in Patients With Diabetes and Acute Kidney Injury

OBJECTIVE

Hypoglycemia is common in patients with diabetes. The risk of hypoglycemia after acute kidney injury (AKI) is not well defined. The purpose of this study was to compare the risk for postdischarge hypoglycemia among hospitalized patients with diabetes who do and do not experience AKI.

RESEARCH DESIGN AND METHODS

We performed a propensity-matched analysis of patients with diabetes, with and without AKI, using a retrospective national cohort of veterans hospitalized between 2004 and 2012. AKI was defined as a 0.3 mg/dL or 50% increase in serum creatinine from baseline to peak serum creatinine during hospitalization. Hypoglycemia was defined as hospital admission or an emergency department visit for hypoglycemia or as an outpatient blood glucose <60 mg/dL. Time to incident hypoglycemia within 90 days postdischarge was examined using Cox proportional hazards models. Prespecified subgroup analyses by renal recovery, baseline chronic kidney disease, preadmission drug regimen, and HbA1c were performed.

RESULTS

We identified 65,151 propensity score-matched pairs with and without AKI. The incidence of hypoglycemia was 29.6 (95% CI 28.9-30.4) and 23.5 (95% CI 22.9-24.2) per 100 person-years for patients with and without AKI, respectively. After adjustment, AKI was associated with a 27% increased risk of hypoglycemia (hazard ratio [HR] 1.27 [95% CI 1.22-1.33]). For patients with full recovery, the HR was 1.18 (95% CI 1.12-1.25); for partial recovery, the HR was 1.30 (95% CI 1.23-1.37); and for no recovery, the HR was 1.48 (95% CI 1.36-1.60) compared with patients without AKI. Across all antidiabetes drug regimens, patients with AKI experienced hypoglycemia more frequently than patients without AKI, though the incidence of hypoglycemia was highest among insulin users, followed by glyburide and glipizide users, respectively.

CONCLUSIONS

AKI is a risk factor for hypoglycemia in the postdischarge period. Studies to identify risk-reduction strategies in this population are warranted.

Competing risks modeling of cumulative effects of time-varying drug exposures

An accurate assessment of drug safety or effectiveness in pharmaco-epidemiology requires defining an etiologically correct time-varying exposure model, which specifies how previous drug use affects the hazard of the event of interest. An additional challenge is to account for the multitude of mutually exclusive events that may be associated with the use of a given drug. To simultaneously address both challenges, we develop, and validate in simulations, a new approach that combines flexible modeling of the cumulative effects of time-varying exposures with competing risks methodology to separate the effects of the same drug exposure on different outcomes. To account for the dosage, duration and timing of past exposures, we rely on a spline-based weighted cumulative exposure modeling. We also propose likelihood ratio tests to test if the cumulative effects of past exposure on the hazards of the competing events are the same or different. Simulation results indicate that the estimated event-specific weight functions are reasonably accurate, and that the proposed tests have acceptable type I error rate and power. In real-life application, the proposed method indicated that recent use of antihypertensive drugs may reduce the risk of stroke but has no effect on the hazard of coronary heart disease events.

Comparative Safety of Sulfonylurea and Metformin Monotherapy on the Risk of Heart Failure: A Cohort Study

BACKGROUND

Medications that impact insulin sensitivity or cause weight gain may increase heart failure risk. Our aim was to compare heart failure and cardiovascular death outcomes among patients initiating sulfonylureas for diabetes mellitus treatment versus metformin.

METHODS AND RESULTS

National Veterans Health Administration databases were linked to Medicare, Medicaid, and National Death Index data. Veterans aged ≥18 years who initiated metformin or sulfonylureas between 2001 and 2011 and whose creatinine was <1.4 (females) or 1.5 mg/dL (males) were included. Each metformin patient was propensity score-matched to a sulfonylurea initiator. The outcome was hospitalization for acute decompensated heart failure as the primary reason for admission or a cardiovascular death. There were 126 867 and 79 192 new users of metformin and sulfonylurea, respectively. Propensity score matching yielded 65 986 per group. Median age was 66 years, and 97% of patients were male; hemoglobin A1c 6.9% (6.3, 7.7); body mass index 30.7 kg/m2 (27.4, 34.6); and 6% had heart failure history. There were 1236 events (1184 heart failure hospitalizations and 52 cardiovascular deaths) among sulfonylurea initiators and 1078 events (1043 heart failure hospitalizations and 35 cardiovascular deaths) among metformin initiators. There were 12.4 versus 8.9 events per 1000 person-years of use (adjusted hazard ratio 1.32, 95%CI 1.21, 1.43). The rate difference was 4 heart failure hospitalizations or cardiovascular deaths per 1000 users of sulfonylureas versus metformin annually.

CONCLUSIONS

Predominantly male patients initiating treatment for diabetes mellitus with sulfonylurea had a higher risk of heart failure and cardiovascular death compared to similar patients initiating metformin.

Comparative Effectiveness of Second-Line Agents for the Treatment of Diabetes Type 2 in Preventing Kidney Function Decline

BACKGROUND AND OBJECTIVES

Diabetes is the leading cause of ESRD. Glucose control improves kidney outcomes. Most patients eventually require treatment intensification with second-line medications; however, the differential effects of those therapies on kidney function are unknown.

DESIGN, SETTING, PARTICIPANTS & MEASUREMENTS

We studied a retrospective cohort of veterans on metformin monotherapy from 2001 to 2008 who added either insulin or sulfonylurea and were followed through September of 2011. We used propensity score matching 1:4 for those who intensified with insulin versus sulfonylurea, respectively. The primary composite outcome was persistent decline in eGFR≥35% from baseline (GFR event) or a diagnosis of ESRD. The secondary outcome was a GFR event, ESRD, or death. Outcome risks were compared using marginal structural models to account for time-varying covariates. The primary analysis required persistence with the intensified regimen. An effect modification of baseline eGFR and the intervention on both outcomes was evaluated.

RESULTS

There were 1989 patients on metformin and insulin and 7956 patients on metformin and sulfonylurea. Median patient age was 60 years old (interquartile range, 54-67), median hemoglobin A1c was 8.1% (interquartile range, 7.1%-9.9%), and median creatinine was 1.0 mg/dl (interquartile range, 0.9-1.1). The rate of GFR event or ESRD (primary outcome) was 31 versus 26 per 1000 person-years for those who added insulin versus sulfonylureas, respectively (adjusted hazard ratio, 1.27; 95% confidence interval, 0.99 to 1.63). The rate of GFR event, ESRD, or death was 64 versus 49 per 1000 person-years, respectively (adjusted hazard ratio, 1.33; 95% confidence interval, 1.11 to 1.59). Tests for a therapy by baseline eGFR interaction for both the primary and secondary outcomes were not significant (P=0.39 and P=0.12, respectively).

CONCLUSIONS

Among patients who intensified metformin monotherapy, the addition of insulin compared with a sulfonylurea was not associated with a higher rate of kidney outcomes but was associated with a higher rate of the composite outcome that included death. These risks were not modified by baseline eGFR.

Diabetes treatment intensification and associated changes in HbA1c and body mass index: a cohort study

BACKGROUND

To describe common type 2 diabetes treatment intensification regimens, patients' characteristics and changes in glycated hemoglobin (HbA1c) and body mass index (BMI).

METHODS

We constructed a national retrospective cohort of veterans initially treated for diabetes with either metformin or sulfonylurea from 2001 through 2008, using Veterans Health Administration (VHA) and Medicare data. Patients were followed through September, 2011 to identify common diabetes treatment intensification regimens. We evaluated changes in HbA1c and BMI post-intensification for metformin-based regimens.

RESULTS

We identified 323,857 veterans who initiated diabetes treatment. Of these, 55 % initiated metformin, 43 % sulfonylurea and 2 % other regimens. Fifty percent (N = 89,057) of metformin initiators remained on metformin monotherapy over a median follow-up 58 months (interquartile range [IQR] 35, 74). Among 80,725 patients who intensified metformin monotherapy, the four most common regimens were addition of sulfonylurea (79 %), thiazolidinedione [TZD] (6 %), or insulin (8 %), and switch to insulin monotherapy (2 %). Across these regimens, median HbA1c values declined from a range of 7.0-7.8 % (53-62 mmol/mol) at intensification to 6.6-7.0 % (49-53 mmol/mol) at 1 year, and remained stable up to 3 years afterwards. Median BMI ranged between 30.5 and 32 kg/m(2) at intensification and increased very modestly in those who intensified with oral regimens, but 1-2 kg/m(2) over 3 years among those who intensified with insulin-based regimens.

CONCLUSIONS

By 1 year post-intensification of metformin monotherapy, HbA1c declined in all four common intensification regimens, and remained close to 7 % in subsequent follow-up. BMI increased substantially for those on insulin-based regimens.

Comparative Effectiveness of Insulin versus Combination Sulfonylurea and Insulin: a Cohort Study of Veterans with Type 2 Diabetes

BACKGROUND

Type 2 diabetes patients often initiate treatment with a sulfonylurea and subsequently intensify their therapy with insulin. However, information on optimal treatment regimens for these patients is limited.

OBJECTIVE

To compare risk of cardiovascular disease (CVD) and hypoglycemia between sulfonylurea initiators who switch to or add insulin.

DESIGN

This was a retrospective cohort assembled using national Veterans Health Administration (VHA), Medicare, and National Death Index databases.

PARTICIPANTS

Veterans who initiated diabetes treatment with a sulfonylurea between 2001 and 2008 and intensified their regimen with insulin were followed through 2011.

MAIN MEASURES

The association between insulin versus sulfonylurea + insulin and time to CVD or hypoglycemia were evaluated using Cox proportional hazard models in a 1:1 propensity score-matched cohort. CVD included hospitalization for acute myocardial infarction or stroke, or cardiovascular mortality. Hypoglycemia included hospitalizations or emergency visits for hypoglycemia, or outpatient blood glucose measurements <60 mg/dL. Subgroups included age < 65 and ≥ 65 years and estimated glomerular filtration rate ≥ 60 and < 60 ml/min.

KEY FINDINGS

There were 1646 and 3728 sulfonylurea monotherapy initiators who switched to insulin monotherapy or added insulin, respectively. The 1596 propensity score-matched patients in each group had similar baseline characteristics at insulin initiation. The rate of CVD per 1000 person-years among insulin versus sulfonylurea + insulin users were 49.3 and 56.0, respectively [hazard ratio (HR) 0.85, 95 % confidence interval (CI) 0.64, 1.12]. Rates of first and recurrent hypoglycemia events per 1000 person-years were 74.0 and 100.0 among insulin users compared to 78.9 and 116.8 among sulfonylurea plus insulin users, yielding HR (95 % CI) of 0.94 (0.76, 1.16) and 0.87 (0.69, 1.10), respectively. Subgroup analysis results were consistent with the main findings.

CONCLUSIONS

Compared to sulfonylurea users who added insulin, those who switched to insulin alone had numerically lower CVD and hypoglycemia events, but these differences in risk were not statistically significant.

Proposal of Standardization to Assess Adherence With Medication Records: Methodology Matters

BACKGROUND

Medication adherence is the process by which patients take their medication as prescribed and is an umbrella term that encompasses all aspects of medication use patterns. Ambiguous terminology has emerged to describe a deviation from prescribed regimen, forcing the European ABC Project to define 3 phases of medication use: initiation, implementation, and discontinuation. However, different measures of medication adherence using medication records are currently available that do not always distinguish between these phases. The literature is lacking standardization and operationalization of the assessment methods.

OBJECTIVE

To propose a harmonization of standards as well as definitions of distinct measures and their operationalization to quantify adherence to medication from medication records.

METHODS

Group discussions and consensus process among all coauthors. The propositions were generated using the authors' experiences and views in the field of adherence, informed by theory.

RESULTS

The concepts of adherence measures within the new taxonomy were harmonized, and the standards necessary for the operationalization of adherence measures from medication records are proposed. Besides percentages and time-to values, the addition of a dichotomous value for the reinitiation of treatment is proposed. Methodological issues are listed that should be disclosed in studies on adherence.

CONCLUSIONS

The possible impact of the measures in adherence research is discussed. By doing this, the results of future adherence research should gain in accuracy. Finally, studies will become more transparent, enabling comparison between studies.

Risk of hypoglycemia following intensification of metformin treatment with insulin versus sulfonylurea

BACKGROUND

Hypoglycemia remains a common life-threatening event associated with diabetes treatment. We compared the risk of first or recurrent hypoglycemia event among metformin initiators who intensified treatment with insulin versus sulfonylurea.

METHODS

We assembled a retrospective cohort using databases of the Veterans Health Administration, Medicare and the National Death Index. Metformin initiators who intensified treatment with insulin or sulfonylurea were followed to either their first or recurrent hypoglycemia event using Cox proportional hazard models. Hypoglycemia was defined as hospital admission or an emergency department visit for hypoglycemia, or an outpatient blood glucose value of less than 3.3 mmol/L. We conducted additional analyses for risk of first hypoglycemia event, with death as the competing risk.

RESULTS

Among 178,341 metformin initiators, 2948 added insulin and 39,990 added sulfonylurea. Propensity score matching yielded 2436 patients taking metformin plus insulin and 12,180 taking metformin plus sulfonylurea. Patients took metformin for a median of 14 (interquartile range [IQR] 5-30) months, and the median glycated hemoglobin level was 8.1% (IQR 7.2%-9.9%) at intensification. In the group who added insulin, 121 first hypoglycemia events occurred, and 466 first events occurred in the group who added sulfonylurea (30.9 v. 24.6 events per 1000 person-years; adjusted hazard ratio [HR] 1.30, 95% confidence interval [CI] 1.06-1.59). For recurrent hypoglycemia, there were 159 events in the insulin group and 585 events in the sulfonylurea group (39.1 v. 30.0 per 1000 person-years; adjusted HR 1.39, 95% CI 1.12-1.72). In separate competing risk analyses, the adjusted HR for hypoglycemia was 1.28 (95% CI 1.04-1.56).

INTERPRETATION

Among patients using metformin who could use either insulin or sulfonylurea, the addition of insulin was associated with a higher risk of hypoglycemia than the addition of sulfonylurea. This finding should be considered by patients and clinicians when discussing the risks and benefits of adding insulin versus a sulfonylurea.

The effects of introducing an electronic prescription system with no copayments

BACKGROUND

To examine the impact of introducing an electronic prescription system with no copayments on the number of prescriptions, the size of prescriptions, and the number of visits and phone calls to primary physicians.

METHODS

Fixed regression models using monthly data on per capita prescriptions claims and consultations between 2009 and 2013 at the municipality level, before and after the introduction of the electronic prescription system.

RESULTS

The electronic prescription system with no copayment increased the number of prescriptions by between 6.0 and 8.1 %. It decreased the average size of each prescription, but it did not decrease the number of consultations.

CONCLUSION

The reduced direct and indirect costs of obtaining prescriptions after the introduction of the electronic prescription system changed the financial incentives facing the patients and physicians. This led to significant changes in the level and size of prescriptions and illustrates the importance of financial incentives.

Effects on Clinical Outcomes of Adding Dipeptidyl Peptidase-4 Inhibitors Versus Sulfonylureas to Metformin Therapy in Patients With Type 2 Diabetes Mellitus

BACKGROUND

Recent studies concluded that dipeptidyl peptidase-4 (DPP-4) inhibitors provide glycemic control but also raised concerns about the risk for heart failure in patients with type 2 diabetes mellitus (T2DM). However, large-scale studies of the effects on cardiovascular outcomes of adding DPP-4 inhibitors versus sulfonylureas to metformin therapy remain scarce.

OBJECTIVE

To compare clinical outcomes of adding DPP-4 inhibitors versus sulfonylureas to metformin therapy in patients with T2DM.

DESIGN

Nationwide study using Taiwan's National Health Insurance Research Database.

SETTING

Taiwan.

PATIENTS

All patients with T2DM aged 20 years or older between 2009 and 2012. A total of 10,089 propensity score-matched pairs of DPP-4 inhibitor users and sulfonylurea users were examined.

MEASUREMENTS

Cox models with exposure to sulfonylureas and DPP-4 inhibitors included as time-varying covariates were used to compare outcomes. The following outcomes were considered: all-cause mortality, major adverse cardiovascular events (MACEs) (including ischemic stroke and myocardial infarction), hospitalization for heart failure, and hypoglycemia. Patients were followed until death or 31 December 2013.

RESULTS

DPP-4 inhibitors were associated with lower risks for all-cause death (hazard ratio [HR], 0.63 [95% CI, 0.55 to 0.72]), MACEs (HR, 0.68 [CI, 0.55 to 0.83]), ischemic stroke (HR, 0.64 [CI, 0.51 to 0.81]), and hypoglycemia (HR, 0.43 [CI, 0.33 to 0.56]) compared with sulfonylureas as add-on therapy to metformin but had no effect on risks for myocardial infarction and hospitalization for heart failure.

LIMITATION

Observational study design.

CONCLUSION

Compared with sulfonylureas, DPP-4 inhibitors were associated with lower risks for all-cause death, MACEs, ischemic stroke, and hypoglycemia when used as add-ons to metformin therapy.

PRIMARY FUNDING SOURCE

None.

National Veterans Health Administration inpatient risk stratification models for hospital-acquired acute kidney injury

OBJECTIVE

Hospital-acquired acute kidney injury (HA-AKI) is a potentially preventable cause of morbidity and mortality. Identifying high-risk patients prior to the onset of kidney injury is a key step towards AKI prevention.

MATERIALS AND METHODS

A national retrospective cohort of 1,620,898 patient hospitalizations from 116 Veterans Affairs hospitals was assembled from electronic health record (EHR) data collected from 2003 to 2012. HA-AKI was defined at stage 1+, stage 2+, and dialysis. EHR-based predictors were identified through logistic regression, least absolute shrinkage and selection operator (lasso) regression, and random forests, and pair-wise comparisons between each were made. Calibration and discrimination metrics were calculated using 50 bootstrap iterations. In the final models, we report odds ratios, 95% confidence intervals, and importance rankings for predictor variables to evaluate their significance.

RESULTS

The area under the receiver operating characteristic curve (AUC) for the different model outcomes ranged from 0.746 to 0.758 in stage 1+, 0.714 to 0.720 in stage 2+, and 0.823 to 0.825 in dialysis. Logistic regression had the best AUC in stage 1+ and dialysis. Random forests had the best AUC in stage 2+ but the least favorable calibration plots. Multiple risk factors were significant in our models, including some nonsteroidal anti-inflammatory drugs, blood pressure medications, antibiotics, and intravenous fluids given during the first 48 h of admission.

CONCLUSIONS

This study demonstrated that, although all the models tested had good discrimination, performance characteristics varied between methods, and the random forests models did not calibrate as well as the lasso or logistic regression models. In addition, novel modifiable risk factors were explored and found to be significant.

The Risk of Opioid Intoxications or Related Events and the Effect of Alcohol-Related Disorders: A Retrospective Cohort Study in German Patients Treated with High-Potency Opioid Analgesics

INTRODUCTION

Intoxications involving prescription opioids are a major public health problem in many countries. When taken with opioids, alcohol can enhance the effects of opioids, particularly in the central nervous system. However, data quantifying the impact of alcohol involvement in opioid-related intoxications are limited.

METHODS

Using claims data from the German Pharmacoepidemiological Research Database (GePaRD), we conducted a retrospective cohort study based on users of high-potency opioid (HPO) analgesics during the years 2005-2009. HPO use was classified as extended-release, immediate-release or both. We calculated incidence rates (IRs) for opioid intoxications or related events as well as adjusted IR ratios (aIRR) comparing HPO-treated patients with alcohol-related disorders (ARDs) to those without ARDs overall and within each HPO category.

RESULTS

During the study period, 308,268 HPO users were identified with an overall IR of 340.4 per 100,000 person-years [95 % confidence interval (CI) 325.5-355.7]. The risk was highest when patients received concomitant treatment with extended- and immediate-release HPOs (IR 1093.8; 95 % CI 904.6-1310.9). ARDs increased the risk during HPO use by a factor of 1.7 and the highest aIRR was seen when comparing patients simultaneously exposed to extended- and immediate-release HPOs with ARDs to those without ARD also after excluding patients with potential improper/non-medical HPO use.

CONCLUSIONS

Physicians should be aware of these elevated risks in HPO patients with ARDs. Active patient education by healthcare providers regarding the risk of opioid intoxications or related events due to alcohol in conjunction with HPOs is warranted.

Durability of oral hypoglycemic agents in drug naïve patients with type 2 diabetes: report from the Swedish National Diabetes Register (NDR)

OBJECTIVE

To analyze the durability of monotherapy with different classes of oral hypoglycemic agents (OHAs) in drug naïve patients with type 2 diabetes mellitus (T2DM) in real life.

METHODS

Men and women with T2DM, who were new users of OHA monotherapy and registered in the Swedish National Diabetes Register July 2005-December 2011, were available (n=17 309) and followed for up to 5.5 years. Time to monotherapy failure, defined as discontinuation of continuous use with the initial agent, switch to a new agent, or add-on treatment of a second agent, was analyzed as a measure of durability. Baseline characteristics were balanced by propensity score matching 1:5 between groups of sulfonylurea (SU) versus metformin (n=4303) and meglitinide versus metformin (n=1308). HRs with 95% CIs were calculated using Cox regression models.

RESULTS

SU and meglitinide, as compared with metformin, were associated with increased risk of monotherapy failure (HR 1.74; 95% CI 1.56 to 1.94 and 1.66; 1.37 to 2.00 for SU and meglitinide, respectively). When broken down by type of monotherapy failure, SU and meglitinide were associated with an increased risk of add-on treatment of a second agent (HR 3.14; 95% CI 2.66 to 3.69 and 2.52; 1.89 to 3.37 for SU and meglitinide, respectively) and of switch to a new agent (HR 2.81; 95% CI 2.01 to 3.92 and 3.78; 2.25 to 6.32 for SU and meglitinide, respectively). The risk of discontinuation did not differ significantly between the groups.

CONCLUSIONS

In this nationwide observational study reflecting clinical practice, SU and meglitinide showed substantially increased risk of switch to a new agent or add on of a second agent compared with metformin. These results indicate superior glycemic durability with metformin compared with SU and also meglitinide in real life.

Association between intensification of metformin treatment with insulin vs sulfonylureas and cardiovascular events and all-cause mortality among patients with diabetes

IMPORTANCE

Preferred second-line medication for diabetes treatment after metformin failure remains uncertain.

OBJECTIVE

To compare time to acute myocardial infarction (AMI), stroke, or death in a cohort of metformin initiators who added insulin or a sulfonylurea.

DESIGN, SETTING, AND PARTICIPANTS

Retrospective cohort constructed with national Veterans Health Administration, Medicare, and National Death Index databases. The study population comprised veterans initially treated with metformin from 2001 through 2008 who subsequently added either insulin or sulfonylurea. Propensity score matching on characteristics was performed, matching each participant who added insulin to 5 who added a sulfonylurea. Patients were followed through September 2011 for primary analyses or September 2009 for cause-of-death analyses.

MAIN OUTCOMES AND MEASURES

Risk of a composite outcome of AMI, stroke hospitalization, or all-cause death was compared between therapies with marginal structural Cox proportional hazard models adjusting for baseline and time-varying demographics, medications, cholesterol level, hemoglobin A1c level, creatinine level, blood pressure, body mass index, and comorbidities.

RESULTS

Among 178,341 metformin monotherapy patients, 2948 added insulin and 39,990 added a sulfonylurea. Propensity score matching yielded 2436 metformin + insulin and 12,180 metformin + sulfonylurea patients. At intensification, patients had received metformin for a median of 14 months (IQR, 5-30), and hemoglobin A1c level was 8.1% (IQR, 7.2%-9.9%). Median follow-up after intensification was 14 months (IQR, 6-29 months). There were 172 vs 634 events for the primary outcome among patients who added insulin vs sulfonylureas, respectively (42.7 vs 32.8 events per 1000 person-years; adjusted hazard ratio [aHR], 1.30; 95% CI, 1.07-1.58; P = .009). Acute myocardial infarction and stroke rates were statistically similar, 41 vs 229 events (10.2 and 11.9 events per 1000 person-years; aHR, 0.88; 95% CI, 0.59-1.30; P = .52), whereas all-cause death rates were 137 vs 444 events, respectively (33.7 and 22.7 events per 1000 person-years; aHR, 1.44; 95% CI, 1.15-1.79; P = .001). There were 54 vs 258 secondary outcomes: AMI, stroke hospitalizations, or cardiovascular deaths (22.8 vs 22.5 events per 1000 person-years; aHR, 0.98; 95% CI, 0.71-1.34; P = .87).

CONCLUSIONS AND RELEVANCE

Among patients with diabetes who were receiving metformin, the addition of insulin vs a sulfonylurea was associated with an increased risk of a composite of nonfatal cardiovascular outcomes and all-cause mortality. These findings require further investigation to understand risks associated with insulin use in these patients.

Pre-study feasibility and identifying sensitivity analyses for protocol pre-specification in comparative effectiveness research

The use of healthcare databases for comparative effectiveness research (CER) is increasing exponentially despite its challenges. Researchers must understand their data source and whether outcomes, exposures and confounding factors are captured sufficiently to address the research question. They must also assess whether bias and confounding can be adequately minimized. Many study design characteristics may impact on the results; however, minimal if any sensitivity analyses are typically conducted, and those performed are post hoc. We propose pre-study steps for CER feasibility assessment and to identify sensitivity analyses that might be most important to pre-specify to help ensure that CER produces valid interpretable results.

A multistate model and an algorithm for measuring long-term adherence to medication: a case of diabetes mellitus type 2

OBJECTIVES

To develop a multistate model and an algorithm for calculating long-term adherence to medication among patients with a chronic disease.

METHODS

We propose definitions of the different states of waiting, persistence, with sufficient supply to implement the prescribed dosing regimen, gaps, nonpersistence, and nonacceptance and an algorithm for transitions between states to describe long-term adherence to medication treatment. The model and algorithm are operationalized for use in a case with a retrospective cohort of patients with type 2 diabetes mellitus, with access to records of prescribed drugs from a Danish diabetes research hospital and records of filled prescriptions at Danish pharmacies from the Danish Health and Medicines Authority.

RESULTS

Calculations of long-term adherence to medication are shown for patients with type 2 diabetes mellitus on metformin and/or simvastatin. The study shows how the prevalence of patients waiting to initiate treatment, patients with supply to implement the prescribed dosing regimen, patients not accepting treatment, and patients discontinuing treatment varies over time.

CONCLUSIONS

The proposed multistate model and algorithm can easily be translated and used for the calculation of adherence to medication in any chronic disease. The model and algorithm take time into account, and thus, changes in incidence rates and prevalence of the different states over time can be estimated on several time scales (calendar time, age of the patient, and time since indication for medication).

An observational study examining the effect of comorbidity on the rates of persistence and adherence to newly initiated oral anti-hyperglycaemic agents

PURPOSE

To examine whether the type of comorbid condition affects medication persistence and adherence in patients initiating oral anti-hyperglycaemic (OAH) therapy.

METHODS

The Irish Health Services Executive pharmacy claims database was used to identify a cohort of incident OAH therapy users (anatomical therapeutic chemical A10B), ≥25 years, between June 2009 and December 2010. Persistence and adherence were examined at 6 and 12 months post-therapy initiation. Comorbidity was ascertained using modified versions of the RxRisk and RxRisk-V indices and classified as either concordant or discordant with diabetes. Adjusted odds ratios (ORs) and 95% confidence intervals (95%CIs) were determined in relation to comorbidity using logistic regression analysis, adjusting for age, gender and type of OAH prescribed.

RESULTS

In the study cohort (n = 21 280), persistence was 74.0% and 62.6% and adherence was 70.0% and 66.7% for all OAHs at 6 and 12 months, respectively. Patients with only concordant comorbidity were significantly more likely to be persistent at 6 (OR 1.45, 95%CI 1.28, 1.65) and 12 months (OR 1.22, 95%CI 1.09, 1.38). Patients with only discordant comorbidity were significantly less likely to be persistent at 6 (OR 0.40, 95%CI 0.35, 0.46) and 12 months (OR 0.43 95%CI 0.38, 0.50) (p < 0.0001). Results were similar for adherence.

CONCLUSION

The study suggests that the persistence and adherence of OAH therapy in incident users are affected by the type of comorbidity present; this may help in identifying effective interventions aimed at optimising medication use.

Treatment persistence, hypoglycaemia and clinical outcomes in type 2 diabetes patients with dipeptidyl peptidase-4 inhibitors and sulphonylureas: a primary care database analysis

AIMS

To investigate therapy persistence, frequency of hypoglycaemia and macrovascular outcomes among type 2 diabetes patients with dipeptidyl peptidase-4 (DPP-4) inhibitors (DPP-4) and sulphonylureas (SU).

METHODS

Data from 19,184 DPP-4 (mean age: 64 years; 56% males) and 31,110 SU users (69 years; 51%) with new prescriptions (index date), without additional antidiabetics except metformin, in 1201 general practises in Germany were analysed. Therapy discontinuation (prescription gap >90 days), hypoglycaemia [International Classification of Diseases (ICD-10)] and macrovascular outcomes (ICD-10) (2-year follow-up) were compared adjusting for age, sex, diabetes duration, metformin, previous hypoglycaemia, health insurance, hypertension, hyperlipidaemia, antihypertensives, lipid-lowering and antithrombotic drugs, microvascular complications and Charlson co-morbidity score using logistic or Cox regression models.

RESULTS

Two years after index date, DDP-4 (non-persistence: 39%) were associated with a lower risk of discontinuation compared to SU (49%) [adjusted hazard ratio (HR): 0.74; 95% confidence interval (CI): 0.71-0.76]. Hypoglycaemias (≥1) were documented in 0.18% patients with DPP-4 and in 1.00% with SU [odds ratio (OR): 0.21; 95%CI: 0.08-0.57]. Hypoglycaemias were significantly associated with incident macrovascular complications (HR: 1.6; 95% CI: 1.1-2.2). Risk of macrovascular events was 26% lower in DPP-4 than in SU users.

CONCLUSIONS

Lack of persistence with antidiabetic therapy is frequently found in primary care patients. DPP-4 was associated with lower therapy discontinuation and a fivefold reduced frequency of patients with hypoglycaemia compared to SU. The low absolute numbers of hypoglycaemias are most likely due to the fact that only severe events were documented. DPP-4 treatment was associated with reduced incidence of macrovascular events relative to SU in type 2 diabetes patients in primary care practises.