Costs of Medication Nonadherence in Patients with Diabetes Mellitus: A Systematic Review and Critical Analysis of the Literature

Value in Health (Impact Factor: 3.28). 08/2009; 12(6):915 - 922. DOI: 10.1111/j.1524-4733.2009.00539.x


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.

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Available from: Maximilian Lebmeier, Jan 27, 2015
    • "Such poor adherence is a barrier to reaching clinical targets [5] and can, therefore, lead to increased diabetes complications and hospitalization [2] [6]. Moreover, poor adherence is likely to be associated with an increase in healthcare costs [7]. "

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    • "It may be that a hospitalization or an ER visit was the precipitating event for the restart of insulin. A large body of literature on T2DM has likewise shown a link between poor adherence and worse outcomes, including an increased risk of hospitalization [24–29]. "
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    ABSTRACT: Although the largest improvement in glycemic control occurs within the first 90 days of insulin therapy, little is known about early persistence on insulin therapy. This research aimed to identify predictors of early discontinuation and of subsequent restart of basal or mixture insulin among patients with type 2 diabetes mellitus (T2DM) and to assess the economic cost associated with such behaviors over a 1-year period. Truven's Health Analytics Commercial Claims and Encounters database was utilized for the study. Logistic regressions were used to examine factors associated with early discontinuation of insulin (basal or mixture) and, among patients who discontinued early, the factors associated with restarting. Cost regressions were estimated using generalized linear models with a gamma distribution and logistic link. Kaplan-Meier survival curves were used to examine time to discontinuation and time to restart among those who discontinued. Multivariate analyses revealed that patient characteristics, prior healthcare resource utilization, comorbid diagnoses, and type of initiated insulin were associated with early discontinuation of insulin and of restarting among patients who discontinued early. Acute care (hospitalization and emergency room) costs were 9.6% higher among patients who discontinued early (P < 0.001), although outpatient, drug, and total costs were significantly lower among individuals who discontinued early. Among the early discontinuation subgroup, restarting insulin was associated with higher costs. Specifically: 11.3% higher acute care costs (P < 0.001), 24.0% higher outpatient costs (P < 0.001), 80.2% higher drug costs (P < 0.001), and 30.3% higher total costs (P < 0.001), compared to patients who discontinued early but did not restart insulin therapy in the 1-year post-period. Among patients with T2DM who were initiated on insulin therapy, early discontinuation of insulin and its subsequent restart were associated with significantly higher acute care costs, which may signal a more complex and challenging subgroup of patients who tend to be less engaged in outpatient care and may have poorer long-term outcomes.
    04/2014; 5(1). DOI:10.1007/s13300-014-0065-z
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    • "Some studies suggest that a limit of 95% should be considered as an acceptable AM rate particularly for certain medical conditions such as HIV/AIDS [4,5]. Evidence shows that non-adherence to medications results in higher health care costs, longer hospitalizations, and increased morbidity and mortality [6-8]. "
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    ABSTRACT: Treatment of diseases such as diabetes mellitus and cardiovascular disorders are highly dependent on medications and particularly adherence to medications to achieve optimal pharmacotherapy outcomes. Several factors can affect a patient's adherence including: knowledge and beliefs about their illness and medications, concomitant psychological disorders, type of therapeutic regimen, and lack of access to medicines. In Iran, a middle income country, essential medicines are highly available and affordable. However, adherence to medications has not been emphasized especially for patients with diabetes and cardiovascular diseases. In the present study, we reviewed the available literature on adherence to medications used to treat diabetes and cardiovascular disorders in Iran. We systematically searched Scopus, Web of Science, PubMed, CINAHL, Google Scholar, Scientific Information Database, and IranMedex using a highly sensitive protocol on July 2012. We retrieved 1003 citations; and two independent researchers screened them for relevant publications. Studies were included if they reported rate or determinants of adherence to diabetes mellitus and cardiovascular medications. Trials on improving interventions were also included. The quality of studies was assessed using appropriate guidelines. Fourteen studies were eligible for data extraction and review. The definition of adherence and the measurement tools used were unclear among studies. Methodological caveats including inappropriate sample size, sampling methods, inclusion/exclusion criteria, and high rate of loss to follow-up were also observed. Nevertheless, adherence rate was reported to be 62.8-86.3% for oral hypoglycemic medications and 38.8-60.0% for cardiovascular medicines. Forgetfulness, lack of knowledge about medical condition and prescribed medications, and concerns about medications efficacy and side effects were consistently reported as barriers to adherence. Patient education plus telephone or short message service follow-ups were reported to improve adherence to oral hypo-glycemic medications. We did not find any high quality trials to include on adherence to cardiovascular medicines. In conclusion, adherence to cardiovascular and diabetes medications is not assured in Iranian patients. Based on the available literature, patient education and reinforcement interventions are required to address this issue. Future studies should employ careful designs and standard tools for assessment of adherence to medications.
    Journal of Diabetes and Metabolic Disorders 12/2013; 12(1):57. DOI:10.1186/2251-6581-12-57
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