Table 1.

Adherence to MTX and associated factors in patients with RA.

Study	Patients Receiving MTX, n	Duration of Followup	Measurement	Adherence to MTX
Study	Patients Receiving MTX, n	Duration of Followup	Measurement	Adherence Definition: Rate	Factors Associated with Adherence
Prospective studies by publication yr
de Klerk, et al¹⁹	23	6 mos	MEMS	Mean percentage of prescribed doses taken: 107%	(+) Less frequent dosing^a (+) Female sex^a
				Mean doses taken at correct dosage: 81%	(+) Better coping^a
				Mean doses taken at correct time: 83%	(−) Better perceived health^a
de Thurah, et al^{23,^b}	85^b	9 mos	CQR score	Median CQR 70.6, IQR 42.1–91.2	None identified
Contreras-Yáñez, et al⁹	93	6 mos	Drug record registry^c	MTX taken correctly ≥ 80% of time: 78% (monotherapy), 14%–49% (combination therapy)	(−) Higher ESR (−) Combination therapy vs monotherapy
Marwaha, et al²⁴	50	3 mos	Patient self-report, interview	Patients who took all MTX doses as prescribed: 92%	NR
Waimann, et al¹²	76	2 yrs	MEMS	Weeks in which patients took MTX as prescribed: 63%	(+) Being married or having significant other^a (+) Lower disease activity^a (+) Better mental health^a
Pasma, et al²⁵	115	1 yr	MEMS	≥ 80% adherent at 3 mos: 91.2%, ≥ 80% adherent at 12 mos: 69.3%	NR
De Cuyper, et al²⁶	129	4 mos	MEMS, CQR score, MARS-5 score, VAS	≥ 80% adherent at 4 mos (MEMS): 91%, ≥ 80% adherent at 16 weeks (CQR): 85.7%, mean MARS-5 score at 16 weeks: 24.2, mean adherence at 16 weeks (VAS): 94%	(+) Comorbidities (+) Better mental health (−) Living alone
Retrospective studies by publication yr
Harley, et al²⁰	1668	1 yr	Claims data	MPR^d ≥ 80%: 64%	NR
Grijalva, et al²¹	NR^e	180 days	Claims data	Median MPR^d 59%, 95% CI 31–82	NR
de Thurah, et al^{22,^a}	941	Median 12.5 mos, IQR 7.3–30.6	Claims data	Mean CMG^f 12.3%^g, 95% CI 11.5–13.2	(+) CRP > 32 ng/l (−) Ulcer/mild liver disease (−) Age > 67 yrs
Cannon, et al¹¹	455	Mean 42.7 ± 31.2 mos	Claims data	MPR^d ≥ 80% over first course of MTX: 84%	(+) White (+) Lower disease activity at enrollment (+) Lower ESR at enrollment
Mueller, et al²⁷	1157	24 mos	Claims data	MPR at 1 yr: 69.7% MPR at 2 yrs: 59.9% MPR at 2 yrs during periods of therapy continuation only: 95%	NR

↵a Indicates adherence to DMARD in general, not specifically to MTX (specific analysis for MTX not reported).
↵b Eighty-five patients at baseline and 65 patients at 9-month followup.
↵c Standardized form that records name, dose, timing, and frequency of MTX use in the 7 days before the interview was completed by the participant.
↵d No. prescribed days of MTX during a course divided by the total duration of days of the course.
↵e Overall, 14,586 patients with RA contributed 28,906 new episodes of medication use; the specific no. patients who received MTX was not reported.
↵f Calculated as the days of treatment gaps divided by total days between first prescription and last prescription. This can be interpreted as the percentage of days not covered by medication.
↵g Implies that 10.5 months were covered by MTX if patients were followed up for 1 year. MTX: methotrexate; RA: rheumatoid arthritis; IQR: interquartile range; MEMS: Medication Event Monitoring System; CQR: Compliance Questionnaire Rheumatology; MARS-5: Medication Adherence Report Scale; VAS: visual analog scale; MPR: medication possession ratio; CMG: continuous measure of medication gap; ESR: erythrocyte sedimentation rate; NR: not reported; CRP: C-reactive protein; DMARD: disease-modifying antirheumatic drugs.