Main characteristics of included studies (n=7)
| First author, country, year [ref.] | Study design | Study population | Medication | Adherence definition | Data source | Timing of measurement | Adherence outcome | Factors potentially associated with adherence | NOS score |
|---|---|---|---|---|---|---|---|---|---|
| Siracusa, USA, 2015 [4] | Prospective cohort | n=12; age: 20.8±9.9 (range 6–48) years; adult: 50%; male: 50%; best FEV1: 100.7±18.2% pred | Iva | Not reported | Electronic monitoring (MEMS); self-report; pharmacy refill data | Prevalent users (≥1 month use) with average monitoring follow-up period of 118±35 days | Mean adherence MEMS-derived: 0.61±0.28 MPR: 0.84±0.31 Self-report: 100% with one exception (at enrolment and 3–4 months later) | 6 | |
| Platt, USA, 2023 [8] | Retrospective cohort | n=191; average age TCP group: 19.9 years; average age non-TCP group: 20.7 years; age range: 0–70 years; male TCP group: 44%; male non-TCP group: 43% | All CFTRm | PDC ≥0.80 | Pharmacy refill data from a health system specialty pharmacy | Prevalent users between January 2017 and December 2020 | Mean PDC TCP group CFTRm# year 1 overall: 0.85±0.17 CFTRm# year 2 overall: 0.83±0.17 CFTRm# year 3 overall: 0.77±0.17 ETI year 1 overall: 0.91±0.13 ETI year 2 overall: 0.91±0.10 Non-TCP group CFTRm# year 1 overall: 0.77±0.22 CFTRm# year 2 overall: 0.80±0.18 CFTRm# year 3 overall: 0.74±0.25 ETI year 1 overall: 0.90±0.14 ETI year 2 overall: 0.86±0.16 | 7 | |
| Olivereau, France, 2020 [17] | Retrospective cohort | n=96; age: 22±9 (range 12– >35) years; adult: 55%; male: 54%; mean FEV1: 77±25% pred | Lum–Iva | PDC ≥0.80 | Pharmacy refill data | First 6 and 12 months after treatment initiation | Mean PDC (capped at 1.00) 6 months: 0.93 12 months: 0.90 Adherent patients (PDC ≥0.80) 6 months: 89% 12 months: 83% | Age (for each additional year): OR 1.13 (95% CI 1.004–1.28) FEV1 % pred (for each additional 1%): OR 1.04 (95% CI 1.005–1.08) Sex, BMI, chronic P. aeruginosa infection and travel time to pharmacy not significant | 8 |
| Mitchell, UK, 2021 [18] | Retrospective cohort | n=35 (MPR available for n=33); age: 29.06±9.54 (range 14–34) years; male: 57% | Iva | Not reported | Refill data from homecare delivery company | 2 years prior to index data (starting Iva) up to 5 years following initiation | Mean MPR 3 months: 0.99±0.03 60 months (n=26): 0.88±0.05 Median MPR 3 months: 1.0 (1.0–1.0) 60 months (n=26): 1.0 (0.78–1.0) | FEV1: p=0.036 (overall MPR–FEV1 change from baseline at 60 months) FEV1: p=0.006 (annual MPR–FEV1 change from previous year) BMI: p=0.027 (overall MPR–BMI); no relationship between overall MPR and BMI change from baseline at 60 months or annual MPR with BMI change from previous years | 7 |
| Tesell, USA, 2019 [19] | Pre–post | n=21; age: 20.1 (range 12–51) years; majority of patients: male¶ | Lum–Iva | PDC ≥0.80 | Pharmacy claims processing system, internally managed PA system and MMIS | 6 months after index date (first pharmacy claim) | Mean PDC: 0.62±0.29 Minority of patients were adherent (PDC ≥0.80)¶ | 5 | |
| Mehta, USA, 2021 [20] | Retrospective cohort | n=2548; age: 23.0±13.7 years; adult: 57.8%; male: 54.4%; mean FEV1 % pred: not available | Iva (30.8%); Lum–Iva (50.6%); Tez–Iva+Iva (18.6%) | Not reported | Pharmacy fill data from national specialty pharmacy | Prevalent users between September 2017 and August 2018 | Mean PDC Total: 0.86±0.15 Iva: 0.84±0.16 Lum–Iva: 0.84±0.15 Tez–Iva+Iva: 0.92±0.11 | PDC according to age Children/adolescents (<18 years) Total: 0.86±0.14 Iva: 0.85±0.15 Lum–Iva: 0.86±0.14 Tez–Iva+Iva: 0.96±0.10 Adults (≥18 years); p-values t-test (versus children/adolescents) Total: 0.85±0.15; p=0.0876 Iva: 0.84±0.16; p=0.3744 Lum–Iva: 0.83±0.15; p=0.0001 Tez–Iva+Iva: 0.91±0.11; p=0.001 | 6 |
| Suthoff, USA, 2016 [21] | Retrospective cohort | n=79; age: 20.8±11.8 years; male: 46% | Iva | MPR ≥0.80 | MSCCD database | Prevalent users between 1 January 2012 and 31 July 2014 | Mean MPR Total: 0.80±0.3 Single-month supply: 0.80±0.3 Multi-month supply: 0.90±0.2 Adherent patients (MPR ≥0.80): 73.4% | 5 |
Data are presented as mean±sd or median (interquartile range), unless otherwise stated. NOS: Newcastle–Ottawa Scale; FEV1: forced expiratory volume in 1 s; Iva: ivacaftor; MEMS: Medication Event Monitoring System; MPR: medication possession ratio; TCP: total care pharmacy; CFTRm: cystic fibrosis transmembrane conductance regulator modulators; Lum: lumacaftor; ETI: elexacaftor–tezacaftor–ivacaftor; PDC: proportion of days covered; BMI: body mass index; P. aeruginosa: Pseudomonas aeruginosa; PA: prior authorisation; MMIS: Medicaid Management Information System; Tez: tezacaftor; MSCCD: MarketScan Commercial Claims and Encounters. #: excluding ETI; ¶: exact percentage not reported.