Table 2

Study outcomes for studies included in meta-analysis

Extracted data
StudySample size (intervention, control)Adherence definition (assessment measure)Intervention groupControl groupp ValueEffect size (Hedges’ g)
(95% CI)
Bailey et al34225 (124, 101)Percentage of patients scored as adherent on all 6 items of a self-report scale (based on Morisky's self-reported scale)Mean=91.9Mean=61.70.0010.44 (0.18 to 0.71)
Berger et al40367 (172, 195)Percentage of patients discontinuing treatment by study endpoint (patient interview)Mean=98.8Mean=91.30.0010.35 (0.14 to 0.55)
Brown et al2969 (36, 33)Percentage of prescribed doses taken over a month (electronic monitoring)Mean (SD)=93.4 (12.3)Mean (SD)=79.1 (28.1)0.66 (0.18 to 1.14)
DiIorio et al4117 (8, 9)Mean number of missed medicines in the last 30 days (self-report questionnaire)Mean (SD)=0.13 (0.35)Mean (SD)=0.98 (1.48)0.73 (−0.21 to 1.67)
DiIorio et al42213 (107, 106)Percentage of doses taken during the intervention period (electronic monitoring)Mean=64Mean=550.090.23 (−0.04 to 0.50)
Farmer et al27211 (126, 85)Percentage of days during a 12-week period in which medication was taken correctly (electronic monitoring)Mean (SD)=77.4 (26.3)Mean (SD)=64.0 (30.8)0.040.47 (0.20 to 0.75)
George et al30343 (170, 173)Percentage of participants classed as adherent (Morisky self-report scale)Mean=72.2Mean= (−0.03 to 0.39)
Golin et al39117 (59, 58)Percentage of prescribed doses taken in the month prior to the study endpoint (CAS)Mean (SD)=76 (27)Mean (SD)=71 (27)0.18 (−0.18 to 0.54)
Hovell et al51188 (92, 96)Cumulative number of doses taken over 9 months (patient interview)Mean (SD)=179.93 (57.01)Mean (SD)=150.98 (73.75)0.44 (0.15 to 0.72)
Konkle-Parker et al 3836 (21,15)Percentage of patients taking >90% of their medications in the last 3–4 weeks (prescription refill data)Mean (SD)=0.93 (0.23)Mean (SD)=0.92 (0.27)0.04 (−0.61 to 0.69)
Maneesriwongul et al3760 (30, 30)Mean percentage of doses taken over the last 4 weeks (self-report using a visual analogue scale)Mean (SD)=97.1 (3.3)Mean (SD)=89.8 (5.6)1.55 (0.98 to 2.12)
Murphy et al5233 (17, 16)Percentage of doses taken during the intervention period (self-report questionnaire)Mean (SD)=0.86 (0.33)Mean (SD)=0.83 (0.36)0.09 (−0.58 to 0.75)
Ogedegbe et al36160 (79, 81)Percentage of days during a 2-month period in which medication was taken correctly (electronic monitoring)Mean=56.9Mean=42.90.0270.35 (0.04 to 0.66)
Pradier et al50202 (123, 121)Percentage of patients deemed to be adherent (taking 100% of doses; self-report questionnaire)Mean=75Mean=610.040.34 (0.02 to 0.65)
Put et al3523 (12, 11)Frequency of non-adherent behaviour over the last 3 months (self-report questionnaire)Mean (SD)=6.9 (1.2)Mean (SD)=8.1 (3.1)0.50 (−0.30 to 1.30)
Remien et al49196 (106, 109)Percentage of doses taken during the previous 2 weeks (electronic monitoring)Mean (SD)=76 (27)Mean (SD)=60 (34)0.52 (0.25 to 0.79)
Safren et al4453 (28, 25)Percentage of prescribed doses taken over the last 2 weeks (self-report questionnaire)Mean (SD)=93 (22)Mean (SD)=94 (10)−0.06 (−0.59 to 0.47)
Sheeran and Orbell2878 (38, 40)Number of once daily doses missed over a 3 week period (self-report questionnaire)Mean=2.68Mean=4.850.050.45 (0.00 to 0.89)
Simoni et al48114 (57, 57)Percentage of doses taken over the last 7 days (electronic monitoring)Mean (SD)=32.3 (42.5)Mean (SD)=29.1 (39.7)0.08 (−0.29 to 0.44)
Smith et al4717 (8, 9)Percentage of participants taking ≥80% of their weekly doses (electronic monitoring)OR=7.8 (2.2 to 28.1)1.08 (0.41 to 1.74)
Solomon et al432087 (1046, 1041)Median % medication possession ratio (prescription refill data)Median=49
IQR=7 to 88
IQR=2 to 86
0.070.08 (−0.01 to 0.17)
Tuldrà et al4677 (36, 41)Percentage of patients with monthly adherence ≥95% (self-reported number of pills taken)Mean=94Mean=690.0080.62 (0.16 to 1.07)
van Es et al3267 (58, 54)Adherence score on a self-report scale based on how often medication was taken (never-always)Mean=7.7Mean= (0.00 to 0.96)
Wagner et al45135 (154, 76)Percentage of doses taken during the intervention period (electronic monitoring)Mean=83.5Mean=86.40.57−0.08 (−0.35 to 0.20)
Weber et al3353 (29, 24)Percentage of patients with monthly adherence ≥95% (electronic monitoring)Mean=70.8Mean=500.0140.69 (0.14 to 1.24)
Williams et al3175 (36, 39)Percentage of doses taken during the intervention period (pill countsMean=58.4Mean=660.162−0.32 (−0.77 to 0.13)