Table 1.
Characteristics of studies reporting on the link between adherence and persistence and health care costs in adult patients with T2DM
| Study | Data source | Adherence measure used | Follow-up duration | Study sample | Treatments studied | Costs reported (cost year, if provided) |
|---|---|---|---|---|---|---|
| Adherence | ||||||
| Ayyagari et al22 (USA) | IMPACT Managed Care Database supplemented with laboratory assessments | Data-driven approach (insulin fills sufficient for entire quarter)a | 1 year | n=13,428; mean age: 54 years; 54% male | Initiation of basal insulin | Hospitalization (inpatient visits),b pharmacy (2010) |
| Chandran et al10 (USA) | Truven Health MarketScan® Commercial and Medicare Supplemental databases | Patients stratified by MPR quintile: least adherent (MPR, 0–0.20) to most adherent (MPR, 0.81–1.00) | 1 year | n=32,361; mean age: 59.1 years; 52.4% male; mean MPR (pen): 0.63; MPR ≥0.80: 33% | Initiating an insulin pen with use of any OAD | Inpatient, outpatient, ER, pharmacy (2011) Total and DM-related |
| Cheng et al18 (Taiwan) | Claims data from the National Health Research Institutes of Taiwan | MPR ≥0.80 | 7 years | n=11,580; mean age: 55.6 years; 53.0% male; mean MPR: 33% (year 1); MPR ≥0.80: 55.1% | OAD | Ambulatory visits, ER, hospitalization, laboratory tests, pharmacy, patient co-pay (2009) |
| Cobden et al25 (USA) | PharMetrics claims database | MPR ≥0.80 | 2 years | n=486; mean age: 45.1 years; 56.4% male; mean MPR: 68%; MPR ≥0.80: 56.2% | Insulin vial and syringe switching to pen use | ER, outpatient, hospitalization, physician visits, pharmacyc (assumed 2005) |
| Egede et al12 (USA) | VHA National Patient Care and Pharmacy Benefits Management databases | MPR ≥0.80 | 5 years | n=740,195; mean age: 65.6 years; 97.8% male | Insulin or OAD | Inpatient, outpatient, pharmacy (2006) |
| Encinosa et al26 (USA) | MarketScan database | Nonadherence = % of days on which the patient did not possess a DM medication; calculated as 1 minus MPR | 1 year | n=56,744; mean age: 54.0 years; 53.4% male | OAD | Hospitalization (admission and ER), hospital care, pharmacy (assumed 2002) |
| Gentil et al27 (Canada) | Longitudinal Quebec Survey on Seniorsd and administrative data from RAMQ | MPR ≥0.80 | 1 year | n=301; 42.9% aged 65–74 years; 35.2% male; MPR ≥0.80: 74.4% | OAD | Hospitalization, ambulatory visits (outpatient and ER), physician fees, outpatient medications (2009 and 2010) |
| Hagen et al19 (USA) | University of Michigan Health Management Research Center | PDC ≥0.80 | 1 year | n=4,978; mean age: 53.0 years; 85.2% male; mean PDC: 0.73; PDC ≥0.80: 57% | OAD | Medical (hospitalization, ER visits, outpatient services), pharmacy, disability costs paid by employer (NR) |
| Hansen et al28 (USA) | MEDSTAT MarketScan Research databases | MPR ≥0.80 | 2 years | n=108,592; mean age: 63.0 years; 50.2% male: MPR during 2 years: 61.3%–73.8% | Monotherapy metformin, pioglitazone, or sulfonylurea | Inpatient, outpatient, pharmacy, patient out-of-pocket expenses (2005) Total and DM-related |
| Hong and Kang14 (South Korea) | Korean National Health Insurance Program database | MPR ≥0.80 | 3 years | n=40,082; mean age: 55.3 years (adherent), 51.1 years (nonadherent); 61.4% male; MPR ≥0.80: 29.4% | OAD | Costs for procedures and therapies for all diseases (including T2DM) (NR) |
| Kleinman et al15 (USA) | Human Capital Management Services Research Reference database | MPR ≥0.80 | 1 year | n=1,588; mean age: 46.5 years; 52.1% male; mean MPR: 60.7%; MPR ≥0.80: 36.5% | Insulin | Medical, pharmacy (2006) |
| Shenolikar et al29 (USA) | North Carolina Medicaid database | MPR (costs determined per 10% change) | 3 years | n=1,073; mean age: 49.5 years; 26.1% male | Initiating pioglitazone | Medical, dental (including regular check-ups), office visits, home health care, inpatient and outpatient care, long-term care facility, prescription medications (NR) Total and DM-related |
| Stuart et al16 (USA) | Medicare Current Beneficiary Surveye | PDC ≥0.80 | 2 years | n=894; mean age: NR; 41.8% male; mean PDC: 74.3%; PDC ≥0.80: 58.2% | OAD | Medical, drug (2010) |
| Persistence | ||||||
| Anderten et al13 (Germany) | Disease Analyser (IMS Health) GP database (1,072 practices) | Early discontinuation: switching to a different basal insulin or another insulin regimen within 90 days of first basal insulin prescription (index date) | 1 year preindex, 1 year postindex | n=2,976;f mean age: 56.1 years/59.1 years (glargine/NPH); 53.2%/53.7% male (glargine/NPH) | Initiating glargine or NPH | Pharmacy, medical services (eg, visit costs based on frequency and complexity, therapeutic remedies and aids, diabetes education and training, and diagnostic procedures) (NR) |
| Ascher-Svanum et al23 (USA) | Truven Health Analytics MarketScan Commercial Claims and Encounters database | Early discontinuation: gap of ≥30 days between end of one prescription and subsequent fill date | 1 year | n=73,399 Mean age: 51.0 years; 54% male | Initiating basal or insulin mix | Hospitalization, ER, outpatient, pharmacy (2011) Total and DM-related costs |
| Hadjiyianni et al24 (Japan) | Claims data from the Japan Medical Center Database | Continuers: no gaps in insulin use; interrupters: ≥1 prescription after gap (≥30 days) in insulin use; discontinuers: no prescription after ≥30-day gap | 1 year | n=827 Mean age: 50.0 years; 71% male |
Initiating basal insulin (previously insulin naïve) | Inpatient, pharmacy (assumed 2013 and 2014) |
| Perez-Nieves et al17 (USA) | OptumHealth Reporting and Insights database | Continuers/persistent users: no therapy gaps ≥30 days; interrupters: ≥1 prescription after the first ≥30-day gap; discontinuers: no prescription claims after first ≥30-day gap | 2 years | n=19,110 Mean age (across groups): 59 years; ~60% male (across groups) |
Initiating basal insulin (previously insulin naïve) | Medical, pharmacy (NR) Total and DM-related costs |
| Wei et al11 (USA) | Pooled data from three retrospective claims database studies (IMPACT database) | Discontinuation: prescription not refilled within 90th percentile of the time (stratified by metric quantity supplied) between first and second fills among patients with ≥1 refill; treatment- persistent days: number of days on treatment without discontinuation or switching; nonpersistence: patients restarting initial study drug after a period without it during follow-up | 1 year | n=4,804 Mean age: 56.0 years; 57% male |
Initiating basal insulin (glargine or detemir) Previously insulin naïve | Pharmacy, total health care costs (NR) Total and DM-related costs (DM costs included medical claims, antidiabetes medications, glucose meters, and test strips) |
| Adherence and persistence | ||||||
| Busyman et al20 (USA) | Large US health plan affiliated with Optum | Adherence: PDC ≥0.80 and MPR ≥0.80; nonpersistence: gap in therapy >90 days | 1 year | n=1,321 Mean age: 53.0 years; 51% male; mean PDC: 0.59; 34% of patients adherent |
Initiating liraglutide | Ambulatory visits, ER, inpatient and other costs, pharmacy (NR) Total and DM-related costs |
Notes:
Effective days supply of insulin associated with each claim =90th percentile of all interfill times for same quantity and insulin type; dichotomous variable for insulin adherence defined in each quarter (consecutive, nonoverlapping 90-day intervals) for each insulin depending on whether patient had insulin supply for all days in that quarter; adherent patients in a quarter were those adherent to ≥1 insulin type.
Medical costs were those paid by the health plan (no further details).
Analysis by adherence status only for all-cause health care costs; no breakdown detailed.
Survey conducted between 2005 and 2008 involving interviews with community-dwelling adults aged ≥65 years (n=2,811).
4,500 beneficiaries inducted into the survey each fall with 3 years’ follow-up; survey contains basic demographics, socioeconomic status, health insurance coverage, health status and functioning, and utilization of and payment for all medical services (reimbursed by Medicare or other payers).
Overall, 2,765 and 1,554 NPH patients identified; after propensity score matching for age, sex, DM duration, antidiabetes comedication, diabetologist care, and Charlson Comorbidity Index, 1,488 patients included in each group.
Abbreviations: DM, diabetes mellitus; ER, emergency room; GP, general practitioner; MPR, medication possession ratio; NPH, neutral protamine Hagedorn insulin; NR, not reported; OAD, oral antidiabetes drug; PDC, proportion of days covered; RAMQ, Régie de l’Assurance Maladie du Quebec (agency responsible for health plans in Quebec); T2DM, type 2 diabetes mellitus; VHA, Veterans Health Administration.