State of the Science: Poor adherence to prescribed medication regimen is a major problem in the treatment of chronic disease. Estimates are that 50% of patients adhere poorly to medication regimens resulting in increased symptomatology, development of complications, increased hospitalizations, premature disability, and death. The interventions that have been tested to date have had little impact on the rates of adherence. As interventions continue to be developed to improve medication adherence, it is important to consider potential modifying factors. One possible factor is the effect of sex differences. The literature to date shows conflicting evidence. Most studies have relied on patient report, a measurement strategy that has been found to be relatively unreliable. In this study we examined gender difference in adherence to medication utilizing electronic monitoring, an accepted standard for adherence assessment.
Objective: To identify the effect, if any, of gender differences on medication adherence in chronic disease.
Design: This study used a cross-sectional descriptive analysis of screening data for a randomized controlled intervention trial designed to test intervention for medication adherence.
Population, Sample, Setting, Years: The sample consisted of 313 subjects with RA over the age of 30 drawn rheumatology practices. The subjects were an older adult population (M = 59 years) and with disease duration of M = 12 years. The sample included 244 females and 69 males, consistent with the gender distribution of the disease. Of these 56% met the poor adherence criterion of < 80% of medication taken in the preceding month. Data were collected over a period of three to four weeks.
Concept/Variables Studied Together: Adherence rates (% of days with correct intake, % of doses received, and % of doses taken within the appropriate time) were measured with electronic monitors (Apex MEMs system) and were examined for gender differences.
Methods: Subjects with RA were recruited for a larger adherence intervention study through private physician practices. Subjects were provided with a Medication Event Monitoring System (MEMS); an electronic monitoring medicine bottle cap that recorded date and time of day of each presumptive dose. Subjects used the monitoring device for a three to four week period as a screening for poor adherence. Data from the cap were downloaded into the computer and adherence estimates were made. In addition subjects were asked to self-report their own estimate of their adherence for the preceding month and the preceding week. Electronic adherence data were analyzed using Student’s t-test for group (gender) differences. Estimates of the comparability of self-reported and electronically monitored data were made using logistic regression to determine odds ratios.
Findings: There were no gender differences in adherence rates (t=-1.5, df 311, p=.122). Sample mean adherence was 51.46% with adherence for males averaging 49.74% and for females 57.54%. Females were somewhat more likely to overestimate adherence using interview data when compared with the electronic data (OR = 2.08, p = .009) although no differences were found for seven day recall of adherence.
Conclusions: These data suggest that when objective data are used to estimate adherence, gender differences in adherence are not found within symptomatic chronic disease. However, it does appear that males are more likely to report adherence rates on interview that are more consistent with electronically monitored data while females are more likely to overreport.
Implications: These data suggest that gender is not likely to play a role in the degree of poor adherence found among patients with symptomatic chronic disease. Studies in the literature, which report group differences, may be biased by reliance upon self-report measures in which women are more likely to overestimate actual adherence than men. This study did not examine whether there may be different mediators of adherence between men and women. Future research is needed to examine the potential interaction effects of other predictors with gender when examining medication adherence in order to determine whether gender should be a consideration in designing adherence interventions.
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