Table 1. Characteristics of studies included in systematic review.
| Study, Year | Region | Patients (% Male) | Mean Age (Years) | Medication | Assessment Method | Nonadherence (NAD) to Medication | Design (Study Quality a ) | |
|---|---|---|---|---|---|---|---|---|
| Definition | Rates, n (%) | |||||||
| Nonadherence based on patient self-reports | ||||||||
| Alkatheri et al., 2014 | Saudi Arabia | 89 (52.8) | 15.0–65.0 | PB | Self-report (MMAS-8) | Score < 7 classified as NAD | 64 (71.9) | CS (M) |
| Ossareh et al., 2014 | Iran | 150 (47.3) | 46.5 ± 16.4 | PB [CaCO3 (n = 136), Al(OH)3 (n = 29), SA (n = 26)] | Self-report (SMAQ) | Responding to any of the question with a NAD answer | 37 (24.7) | CS (M) |
| Self-report (DIPQ) | Taking < 66% of prescribed medication | CaCO3, 66 (48.5); Al(OH)3, 26 (89.7); SA, 11 (42.3) | ||||||
| Chater et al., 2014 | UK | 221 (52.0) | 58.1 ± 14.2 | PB [CaCO3, Al(OH)3, SA, Ca(C2H3O2)2] | Self-report (7-item MARS) | Score ≤ 28 classified as low adherers | 68 (30.8) | CS (M) |
| Arenas et al., 2013 | Spain | 181 (56.9) | 59.9 (21–86) | PB [CaCO3, Al(OH)3, Ca(C2H3O2)2 SA, LC], CM, Vitamin D | Self-report (SMAQ) | Responding to any of the question with a NAD answer | 110 (60.8) (at baseline visit); 79 (71.8) (at 6 month) | P (M) |
| Santana & Diaz, 2013 | Spain | 106 (71.0) | 61.0 ± 13.0 | PB [CaCO3, Al(OH)3, SA, Ca(C2H3O2)2], CM (Cinacalcet) | Self-report (SMAQ) | Responding to any of the question with a NAD answer | 40 (37.7) | CS (M) |
| Theofilou, 2013 | Greece | 168 (62.5) | 62.0 | NA | Self-report (5-item MARS) | Score < 20 classified as low adherers | 42 (25.0) | CS (M) |
| Martins et al., 2013 | Brazil | 502 (66.3) | 47.0 ± 13.3 | PB | Interview | Reporting missed dose | 330 (65.7) | CS (M) |
| Garcia-Llana et al., 2013 | Spain | 30 (60.0) b | 60.6 ± 16.7 | AHT (n = 17); PB (n = 25) | Self-report (MGLT-4) | Responding to any of the question with a NAD answer | AHT, 15 (90.9); PB, 17 (68.4) | CS (M) |
| Rosenthal Asher et al., 2012 | USA | 85 (40.0) b | 55.9 ± 13.2 | NA | Self-report (ITAS-M) | Score ≤ 9 classified as low adherers | 11 (13.0) | P (M) |
| Wileman et al., 2011 | UK | 76 (60.5) | 63.1 ± 15.4 | PB | Self-report (MAQ) | Responding to any of the question with a NAD answer | 11 (14.5) | CS (M) |
| Neri et al., 2011 | Italy | 1,238 (-) | 61.7 ± 14.5 | NA | Self-report (MGLT-4) | Responding to any of the question with a NAD answer | 644 (52.0) | P (M) |
| Cukor et al., 2009 | USA | 65 (46.0) b | 51.1 ± 13.0 | NA | Self-report (ITAS-M) | Score ≤ 9 classified as low adherers | 24 (37.0) | P (M) |
| Garcia et al., 2008 | Spain | 47 (63.0) b | 70.0 ± 14.5 | PB | Self-report (MGLT-4) | Responding to any of the question with a NAD answer | 24 (52.3) | CS (M) |
| Hirth et al., 2008 | Multinational c | 7,852 (-) | 62.4 ± 14.6 | AHT, PB, CM | Self-report | Reporting cost related NAD | 1052 (13.4) | CS (M) |
| Lindberg et al., 2007 | Sweden | 150 (60.0) b | 63.6 ± 14.3 | AHT, PB, CM, HDS | Self-report | Differences in the self-reported drug and prescription record | 120 (80.4) | CS (W) |
| Holley & DeVore, 2006 | USA | 39 (44.0) b | 67% over 50 | NA | Self-report | Missing prescription filling | 11 (22.0) | CS (W) |
| Reporting missed dose | 21 (39.0) | |||||||
| Rahman & Griffin, 2004 | USA | 270 (53.0) | 60.4 ± 16.0 | AHT (n = 205) | Self-report | Reporting missed dose | 47 (23.0) | CS (M) |
| Horne et al., 2001 | UK | 47 (48.9) | 49.0 ± 17.3 | NA | Self-report (BMQ) | Responding to any of the question with a NAD answer | 27 (57.4) | CS (M) |
| Caraballo Nazario et al., 2001 | USA | 53 (41.7) | 51.5 ± 14.3 | AHT, PB | Structured Interview | Reporting missed dose | 39 (75.0) | CS (M) |
| Gago et al., 2000 | Spain | 121 (56.2) | 62.8 ± 12.6 | AHT (n = 49); PB [CaCO3 (n = 104); Al(OH)3 (n = 39)] | Self-report | Differences in the self-reported drug and prescription record | AHT, 6 (12.5); CaCO3, 14 (14.0); Al(OH)3, 4 (12.5) | CS (W) |
| Kaplan et al., 1994 | USA | 30 (40.0) | 40.5 (14–69) | AHT, PB | Self-report | Reporting missed dose | 20 (66.7) | CS (M) |
| Blanchard et al., 1990 | USA | 40 (50.0) | 50.4 ± 16.4 | Ca Supplements, PB, Vitamins | Self-report | Reporting missed dose | 11 (27.5) | P (M) |
| Nonadherence based on objective measures | ||||||||
| Park et al., 2014 | USA | 11,732 (56.2) | 69.4 ± 12.7 | AHG (n = 3,819); AHT (n = 9,863); AL (n = 4,607); CM (n = 2,436); PB (n = 7,753) | MPR | MPR < 80% (Poor adherence) | AHG: 2,338 (61.2); AHT: 4,098 (41.5); AL: 2,118 (46.0); CM: 1,587 (65.1); PB: 6,068 (78.3) | R (M) |
| Porter 2013 | USA | 96 (53.1) | 52.5 ± 14.6 | PB (SA), CM, Vitamin D | Refill per EMR | Medication course either not started or partially completed | 35 (36.5) | R (M) |
| Lee at al., 2011 | USA | 4,923 (53.3) | 61.8 ± 13.8 | CM (Cinacalcet) | Refill | ≥ 180 days refill gap | 2,247 (45.6) | R (M) |
| MPR | MPR < 0.8 (Poor adherence) | 1,304 (26.5) | ||||||
| Gincherman et al., 2010 | USA | 79 (43.0) | 51.0 ± 13.0 | CM (Cinacalcet) | MPR | MPR < 0.8 (Poor adherence) | 56 (70.9) | R (M) |
| Chiu et al., 2009 | USA | 233 (58.0) | 52.9 ± 14.7 | PB [CaCO3, Al(OH)3, Ca(C2H3O2)2, SA, LC] | Pill count | Taking < 80% of prescribed pills | 144 (62.0) | CS (M) |
| Curtin et al., 1997 | USA | 135 (47.0) | 63.2 ± 13.8 | AHT (n = 83); PB (n = 98) | MEMS | Instance of bottle opening | AHT, 77 (92.8); PB, 96 (97.9) | P (M) |
| Nonadherence based on biochemical measures | ||||||||
| Wileman et al., 2015 | UK | 112 (61.6) | 60.5 ± 16.9 | PB | SPL | SPL > 5.0 mg/dL | 79 (70.5) | CS (M) |
| O’Connor et al., 2008 | UK | 73 (60.3) | 51.9 ± 14.7 | PB | SPL | SPL ≥ 5.5 mg/dL | 40 (55.0) | P (M) |
| Tijerina, 2006 | USA | 26 (0.0) | 30–56 | PB | SPL | SPL > 6.0 mg/dL | 16 (61.5) | CS (M) |
| Saounatsou, 1999 | Greece | 60 (53.3) | 49.4 | PB | SPL | SPL > 5.0 mg/dL | 17 (28.3) | CS (M) |
| Leggat et al., 1998 | USA | 6,251 (49.7) | 57.8 ± 15.5 | PB | SPL | SPL > 7.5 mg/dL | 1,383 (22.1) | R (M) |
| Bame et al., 1993 | USA | 1229 (47.1) | 56.7 (18–90) | PB | SPL | SPL > 6.0 mg/dL | 612 (49.8) | CS (M) |
| Weed-Collins & Hogan, 1989 | USA | 30 (43.0) | 25–80 | PB | SPL | SPL > 5.5 mg/dL | 19 (64.0) | CS (M) |
| Betts & Crotty, 1988 | USA | 46 (33.0) | 41–60 | PB | SPL | SPL > 5.0 mg/dL | 35 (76.1) | CS (M) |
| Cummings et al., 1982 | USA | 116 (54.0) | 54.8 (21–76) | PB | SPL | SPL > 5.5 mg/dL | 81 (70.0) | CS (M) |
| Wenerowicz et al., 1978 | USA | 19 (68.4) | 36.0 (19–70) | PB | SPL | SPL > 4.5 mg/dL | 13 (68.4) | CS (M) |
| Nonadherence based on multiple measures | ||||||||
| Sgnaolin et al., 2012 | Brazil | 65 (49.2) | 59.1 ± 14.7 | AHT, PB | SPL | SPL > 5.5 mg/dL | 25 (38.5) | CS (M) |
| Self-report (MGLT-4) | Responding to any of the question with a NAD answer | 36 (55.4) | ||||||
| Chan et al., 2012 | Malaysia | 188 (48.9) | 58.2 ± 10.5 | PB | SPL | SPL > 5.0 mg/dL | 63 (33.5) | CS (M) |
| Self-report (DDFQ) | Score ≤ 3 classified as low adherers | 93 (49.5) | ||||||
| Arenas et al., 2010 | Spain | 165 (63.0) | 65.2 ± 14.7 | PB [Al(OH)3, Ca(C2H3O2)2, SA] | SPL | SPL > 5.5 mg/dL | 23 (13.9) | CS (M) |
| Self-report (SMAQ) | Responding to any of the question with a NAD answer | 66 (40.0) | ||||||
| Lin & Liang, 1997 | China | 86 (-) | 55.0 (45.0) | PB | MCA | SPL > 5.0 mg/dL | 52 (61.0) | CS (M) |
| Nurse assessment | 26 (30.8) | |||||||
| Self-report | 20 (23.6) | |||||||
| Cleary et al., 1995 | USA | 51 (45.1) b | 51.0 ± 17.0 | AHT, PB, Vitamin D | SPL | SPL > 4.5 mg/dL | 23 (45.1) | CS (M) |
| Structured Interview | Reporting missed dose | 30 (60.0) | ||||||
| Curtin et al., 1999 | USA | 135 (46.7) | 63.2 ± 13.8 | AHT (n = 69), PB (74) | Self-report (BMQ) | Overdosing, under dosing, or missing an entire day’s dose | AHT, 14 (20.3); PB, 34 (45.9) | CS (M) |
| Pill count | Number of pills added at each refill | AHT, 63 (91.3); PB, 73 (98.6) | ||||||
| MEMS | Instance of bottle opening | AHT, 66 (95.7); PB, 72 (97.3) | ||||||
Note: Conversion factor for unit: SPL in mg/dL to mmol/L, x0.3229. Abbreviations: AHG, antihyperglycemics; AHT, antihypertensives; AL, antilipidemics; BMQ, brief medication questionnaire; CM, calcimimetics; DDFQ, dialysis diet and fluid nonadherence questionnaire; DIPQ, drug intake percentage questionnaire; EMR, electronic medical record; HDS, herbal and dietary supplement; ISAI, Iowa self-assessment inventory; ITAS-M, modified immunosuppressive therapy adherence scale; LC, lanthanum carbonate; MAQ, medication adherence questionnaire; MARS, medication adherence report scale; MCA, multi-method compliance assessment (including: laboratory assessment, nurse assessment, and patient self-report); MEMS, medication event monitoring system; MGLT-4, Morisky 4-item Green Levine test; MMAS-8, Morisky 8-item medication adherence scale; MPR, medication possession ratio; PB, phosphate binder; SA, sevelamer hydrochloride; SMAQ, simplified medication adherence questionnaire; SPL, pre-dialysis serum phosphate level; Study design (CS, cross-sectional; P, prospective; R, retrospective); NA, not available.
aEffective public health practice project (EPHPP) quality assessment tool for quantitative studies. Study quality (S, strong; M, moderate; W, weak).
bSubsample of haemodialysis patients.
cTwelve industrialized countries (Australia/ New Zealand, Belgium, Canada, France, Germany, Italy, Spain, Sweden, and UK, twenty facilities each; Japan, sixty facilities; and USA, eighty facilities).