Arthritis & Rheumatism, Volume 63,
November 2011 Abstract Supplement

Abstracts of the American College of
Rheumatology/Association of Rheumatology Health Professionals
Annual Scientific Meeting
Chicago, Illinois November 4-9, 2011.

Identifying Predictors of Medication Adherence In Patients with Rheumatoid Arthritis.

Frazier, Elizabeth G. Salt and Susan K.

Background/Purpose:

Despite the many effective disease modifying anti-rheumatic drugs (DMARDs) available to treat rheumatoid arthritis (RA), medication adherence is a significant problem. Inconsistencies in reported research have resulted in a lack of predictors of medication adherence in patients with RA. The purpose of this study was to: 1) describe self-reported medication adherence to DMARDs; 2) compare demographic (age, residence, marital status, employment status, years of education, and race) and clinical (duration of disease and number of medications) factors of adherent and nonadherent individuals; and 3) determine the predictive power of demographic and clinical factors for DMARD adherence.

Methods:

This study will use a cross-sectional descriptive, predictive design in a sample of 108 patients with RA. A validated, self-report scale using various cut-points (used in prior research, mean, and median) will be used to determine medication adherence. Logistic regression modeling, independent samples t-tests, and Chi square analyses were used to analyze these data.

Results:

Ninety percent of the individuals (mean age 52 ± 13 years, 76% female) reported adherence with their prescribed DMARD prescriptions using a cut-point of 39 for the Medication Adherence Report Scale (Horne and Weinman, 2002). Race was the only demographic or clinical difference between the adherent and nonadherent group (p=0.04); white individuals reported significantly more adherence with their prescribed DMARDs when compared to non-white individuals (Table 1). Similarly, race (OR= 3.34–10.1; p< 0.05) and the number of medications taken (OR=1.7; p< 0.05) were predictors of medication nonadherence using logistic regression models with 3 cut-points (Table 2).

Table 1. Characteristics of Participants.

Variable	Total sample (n = 108)	Adherent group (n = 98)	Nonadherent group (n = 10)	p value
Age in years	52 ± 13	52 ± 14	53 ± 9	0.77
Gender female	82 (76%)	75 (76%)	6 (68%)	0.69
Ethnicity	89 (83%)	84 (86%)	5 (56%)
Caucasian	14 (13%)	11 (11%)	3 (33%)
African American/Other	4 (4%)	3 (3%)	1 (11%)	0.04
Education in years	13 ± 3	13 ± 3	12 ± 3	0.81
Marital status
Married/cohabit	62 (58%)	56 (57%)	6 (67%)	0.74
Widowed	7 (7%)	7 (7%)	0
Divorced/Separated	20 (19%)	19 (19%)	1 (11%)
Single/ Never Married	18 (17%)	16 (16%)	2 (22%)
Employment
Employed full-time	27 (26%)	25 (26%)	2 (22%)	0.72
Employed part-time	7 (7%)	7 (7%)	1 (11%)
Unemployed	10 (9%)	10 (10%)	0
Sick leave/disability	35 (33%)	33 (34%)	2 (22%)
Homemaker	7 (7%)	6 (6%)	1 (11%)
Retired	20 (19%)	17 (17%)	3 (33%)
Residence location
Urban	55 (51%)	48 (53%)	7 (78%)	0.18
Rural	45 (42%)	43 (47%)	2 (22%)
Years since diagnosis	10 ± 10	10 ± 10	11 ± 8	0.73
Total number of RA medications	2 ± 1	2 ± 1	3 ± 2	0.43
Values are mean + SD or frequency (%), May not total to 100% due to some missing data points
Variables compared with independent t tests or Chi square analyses based on level of measurement
For those variables with no cases in a cell, categories were collapsed to ensure the assumptions of Chi square were met prior to analysis

Table 2. Predictors of Adherence to DMARDs.

Using the cut point from a prior research study
Factor	Odds Ratio	Significance	95% Confidence Interval
Factor	Odds Ratio	Significance	lower	upper
Race (white versus nonwhite)	10.10	0.01	1.66	61.40
Residence (rural versus urban)	7.52	0.10	83.33	0.70
Duration of disease	1.00	0.83	1.01	1.00
Years of education	1.09	0.61	1.50	0.79
Total number of medications taken for RA	1.26	0.51	2.53	0.63
Marital status (married versus not married)	1.44	0.75	0.151	13.68
Employment (full time versus not full-time)	2.19	0.52	21.3	0.21
Age	1.01	0.80	0.94	1.08
Using the median cut point

Factor	Odds Ratio	Significance	95% Confidence Interval
			lower	upper
Race (white versus nonwhite)	2.67	0.12	0.78	9.17
Residence (rural versus urban)	1.54	0.38	0.58	4.08
Duration of disease	1.00	0.18	1.01	0.99
Years of education	1.03	0.73	0.89	1.19
Total number of medications taken for RA	1.69	0.02	2.63	1.09
Marital status (married versus not married)	2.76	0.17	11.63	0.66
Employment (full time versus not full-time)	2.71	0.20	0.59	12.40
Age	0.99	0.71	1.04	0.97
Using the mean cut point

Factor	Odds Ratio	Significance	95% Confidence Interval
			lower	upper
Race (white versus nonwhite)	3.34	0.05	1.02	10.95
Residence (rural versus urban)	1.87	0.22	0.70	5.05
Duration of disease	1.00	0.11	1.01	0.99
Years of education	1.04	0.59	1.21	0.89
Total number of medications taken for RA	1.37	0.16	2.11	0.89
Marital status (married versus not married)	2.11	0.30	8.62	0.51
Employment (full time versus not full-time)	2.62	0.21	0.58	11.79
Age	1.00	0.88	1.04	0.97

Conclusion:

Race and taking an increased number of medications for RA were independent predictors of medication adherence in this sample of patients with RA. These findings further define a health disparity. Future research is needed to develop a full understanding of this problem and thus, to improve patient outcomes.

To cite this abstract, please use the following information:
Frazier, Elizabeth G. Salt and Susan K.; Identifying Predictors of Medication Adherence In Patients with Rheumatoid Arthritis. [abstract]. Arthritis Rheum 2011;63 Suppl 10 :868
DOI:

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