TABLE 1.
Study Characteristics
| First author (year) | Country | Study design | Adherence data source | n a | Time | Baseline characteristics | Intervention characteristics | ||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Mean age (SD) (y)b | Sex (%) | Mean A1C (SD) | Mean adherence, % (SD) | Insulin type | Waste? | Adherence measurec | Glycemic measure | ||||||
| Ayyagari (2015) | United States | RCT | IMPACT (2001-2010) (United States) | 4,876 | 1 y | 54 | M: 54 F: 46 |
NA:9.0 (2.4);A:9.3 (2.1) | NR | Basal insulin | Not noted | Interfill periods | Change in A1c |
| Cramer (2005) | United States | RCT | VA PBM (2001– 2002) (Eastern United States and Puerto Rico) | 6,222 | 2 y | NR | NR | 8.0 (1.7) | 77 (17) | Any | Not factored (assumed constant) | Similar to MPR | Change in A1c |
| Donnelly (2007) | Scotland | RCT | DARTS/ MEMO Collaboration (1995-2001) (Tayside, Scotland) | 1,099 | 6.75 y | 62 (12) | M: 52 F: 48 |
8.5 (1.3) | 71 (18) | Not noted | Not noted | Similar to PDC | Change in A1c |
| Eby (2013) | United States | RCT | Innovus InVision (2006-2010) (United States) | 760 | 1 y | P:54 (11)V:56 (12) | P: M: 55 F: 45 V: M: 54 F: 46 |
NR | NR | Mealtime insulin (RAI, PMX insulin) | Not noted | aMPR | Change in A1c |
| Egede (2014) | United States | RCT | VA PBM (1997-2006) (Southeastern United States) | NR | 5.4 y | 66 (12) | M: 97 F: 3 |
NR | NR | Not noted | Not noted | aMPR | Change in A1c |
| Grabner (2013) | United States | RCT | HIRD (United States) | 1,466 | 1 y | 52 (NR) | M: 57 F: 43 |
P: 9.5 (2.0);V: 9.4 (2.2) | NR | Insulin glargine | No waste assumed | aMPR | Change in A1c |
| Hood (2021) | United States | RCT | VA PBM (2014– 2017) (United States) | 951 | 9 mo | 63 (NR) | M: 98 F: 2 |
9.3 (1.7) | 73 (19) | Any | Not noted | PDC | Change in A1c |
| Kindmalm (2007) | Sweden | RCT | 6 health centers (Skaraborg, Sweden) | 102 | 1 y | 64 (NR) | NR | NR | NR | Not noted | Not noted | Similar to MPR | A1c levels at the end |
| Magny-Normilus (2021) | United States | RCT | SureScripts (2012 - 2013) (Boston, MA) | 122 | 4 mo | I:65 (11)C:64 (12) | I: M: 42 F: 58 C: M: 27 F: 73 |
I: 8.4 (2.0)C: 8.5 (2.3) | NR | Any | Partial waste assumed | aMPR | Change in A1c |
| Slabaugh (2015) | United States | RCT | Humana (MAPD plan) (2009-2012) (United States) | 1,335 | 2 y | P:69.4 (8.6)V: 70.1 (8.6) | P: M: 53 F: 47 V: M: 57 F: 43 |
NR | NR | Basal insulin | Not noted | aMPR PDC | Change in A1c |
| Wei (2014) | United States | RCT | IMPACT (2006-2012); Humana (2006-2012) (United States) | 2,809 | 1 y | 60 (NR) | M: 50 F: 50 |
IMPACT: 8.6 (1.7); Humana: 8.2 (1.5) | NR | Not noted | Not noted | aMPR | Change in A1c |
a This represents the patients receiving insulin who are represented in the systematic review/meta-analysis.
b This represents the whole cohort described in the study, including but not limited to the ones receiving insulin.
c The MPR was noted as being adjusted if any modifications to a standard MPR calculation was made. A = adherent; aMPR = adjusted medication possession ratio; BBI = basal-bolus insulin; DARTS = Diabetes Audit and Research in Tayside; C = control group; DET-C = continued insulin detemir; F = female; GLA-C = continued insulin glargine; A1c = hemoglobin A1c; HIRD = HealthCore Integrated Research Database; I = intervention group; M = male, MAPD = Medicare Advantage with Prescription Drug; MEMO = Medicine Monitoring Unit; mo = months; MPR = medication possession ratio; NA = nonadherent; NR = not reported; P = pen group; PBM = pharmacy benefit management; PDC = proportion of days covered; PMX = premixed; RAI = rapid-acting insulin; RCT = randomized controlled trial; V = vial group; VA = Veterans Administration; y = years.