Basal insulin persistence, associated factors, and outcomes after treatment initiation among people with type 2 diabetes mellitus in the US

Abstract

Objective To assess basal insulin persistence, associated factors, and economic outcomes for insulin-na€ ıve people with type 2 diabetes mellitus (T2DM) in the US. Research design and methods People aged 18 years diagnosed with T2DM initiating basal insulin between April 2006 and March 2012 (index date), no prior insulin use, and continuous insurance coverage for 6 months before (baseline) and 24 months after index date (follow-up period) were selected using de-identified administrative claims data in the US. Based on whether there were 30 day gaps in basal insulin use in the first year post-index, patients were classified as continuers (no gap), interrupters (1 prescription after gap), and discontinuers (no prescription after gap). Main outcome measures Factors associated with persistence -assessed using multinomial logistic regression model; annual healthcare resource use and costs during follow-up period -compared separately between continuers and interrupters, and continuers and discontinuers. Results Of the 19,110 people included in the sample (mean age: 59 years, 60% male), 20% continued to use basal insulin, 62% had 1 interruption, and 18% discontinued therapy in the year after initiation. Older age, multiple antihyperglycemic drug use, and injectable antihyperglycemic use during baseline were associated with significantly higher likelihoods of continuing basal insulin. Relative to interrupters and discontinuers, continuers had fewer emergency department visits, shorter hospital stays, and lower medical costs (continuers: $10,890, interrupters: $13,674, discontinuers: $13,021), but higher pharmacy costs (continuers: $7449, interrupters: $5239, discontinuers: $4857) in the first year post-index (p < 0.05 for all comparisons). Total healthcare costs were similar across the three cohorts. Findings for the second year post-index were similar. Conclusions The majority of people in this study interrupted or discontinued basal insulin treatment in the year after initiation; and incurred higher medical resource use and costs than continuers. The findings are limited to the commercially insured population in the US. In addition, persistence patterns were assessed using administrative claims as opposed to actual medicationtaking behavior and did not account for measures of glycemic control. Further research is needed to understand the reasons behind basal insulin persistence and the implications thereof, to help clinicians manage care for T2DM more effectively. ARTICLE HISTORY

Cost of medication adherence and persistence in type 2 diabetes mellitus: a literature review

“…23 Increased pharmacy costs were offset by savings in other areas in three of the other persistence studies, although not enough to result in a reduction in total health care costs in more persistent patients 11,17,24. One US claims analysis reported lower all-cause medical costs (costs not disaggregated) in the first year after treatment initiation in patients who continued basal insulin compared with interrupters or discontinuers ( P ≤0.022; Figure 3A), but the higher pharmacy costs also incurred by this group resulted in no difference in total health care costs (medical plus pharmacy) between patient cohorts 17. Using Japanese claims data, it was also shown that higher pharmacy expenditures in patients with T2DM who continued basal insulin therapy were not completely offset by significant reductions in inpatient costs reported in this group compared with interrupters or discontinuers ( P ≤0.039; Figure 3B).…”

“…Pharmacy/drug/medication costs were specifically reported as being included in the analyses of all studies, 13 reported including inpatient, hospitalization, and/or emergency room (ER) costs, and outpatient or ambulatory costs were reported in 10 studies. Some studies were, however, vague about what expenses were actually considered, instead just referring to “medical” or “total” costs in their methodologies 11,13–17. Only two studies considered the costs of nonadherence outside the health care system: patient co-payments were included in one study and out-of-pocket expenses were included in another 18,19.…”

“…Three studies defined a gap of 30 days as demonstrating nonpersistence,17,23,24 while one defined a longer gap of 90 days 13. Two studies provided a definition of “interrupters” as patients who received at least one prescription after a gap 17,24. A data-driven approach to the measurement of persistence was taken in one study, again due to the issues of using days supply encountered with injectable treatments 11…”

“…In contrast, patients who exhibited good adherence or persistence with medication were mostly reported to have increased pharmacy costs, which is not unexpected given that these are the individuals who, unlike nonadherent or nonpersistent patients, consistently take their medications as prescribed and continue to fill prescriptions as recommended. Several studies demonstrated that the beneficial effects of good adherence on medical costs such as hospitalization were sufficient to offset increases in drug expenditure such that total health care costs were either not significantly different between adherent and nonadherent patients11,16,17,19,22,24 or were significantly reduced 10,12,26,28. Rarely were total health care costs reported to be increased in adherent or persistent patients; and where this was the case, the significantly higher pharmacy costs were cited as the primary driver 18,20…”

“…For example, identified studies varied widely with respect to methodologies, measurement of adherence or persistence, patient populations, and treatments, making direct comparisons between them impractical. Given the range of different treatment options evaluated, it was clear that patients are at different points in the disease continuum across studies and ranged from the newly diagnosed14 to those being initiated or established on insulin 17,25. This has important cost implications, since those with T2DM of longer duration are likely to experience more complications and thus exert a greater economic burden.…”