Poor adherence to oral and topical medication in 3096 dermatological patients as assessed by the Morisky Medication Adherence Scale-8

DEAR EDITOR, Recent studies have shown that adherence to treatment is an important factor for good therapeutic outcome in various chronic disorders such as hypertension and diabetes. In dermatology, patient nonadherence to therapy is also very problematic and has been associated with poor therapeutic outcomes in common skin diseases. Although there is no ‘gold standard’ to measure medication adherence, an eight-item self-reported scale called the Morisky Medication Adherence Scale-8 (MMAS-8) has been developed by Morisky et al. MMAS-8 originally targeted oral medication for hypertensive patients, but it is now applied to measure medication adherence in a wide range of disorders such as diabetes and osteoporosis. However, there are no reports of studies investigating dermatological adherence using this scale. Therefore, this study assessed medication adherence for oral and topical remedies using a translated version of MMAS-8 together with other socioeconomic background factors in 3096 Japanese dermatological patients. This study was conducted among patients registered in a monitoring system established by Macromill Inc. (Tokyo, Japan). The registered individuals (n = 4144) were prescreened in terms of skin diseases and their intention to participate in this study. In total 3096 eligible patients were enrolled, 1327 with atopic dermatitis, 751 with urticaria, 237 with psoriasis and 781 with tinea. Our web-based questionnaire included the following items: age, sex, marital status, annual income, employment status, educational status, smoking habit, alcohol consumption, frequency of hospital visits, main healthcare institution, oral or topical medication, experience of the effectiveness of oral medication, experience of the effectiveness of topical medication, experience of adverse events associated with oral medication, experience of adverse events associated with topical medication, overall satisfaction with treatment, MMAS-8 for oral medication and MMAS-8 for topical medication. The original MMAS-8 was translated into Japanese according to international guidelines. Forward translation of the original questionnaire was undertaken by translation from English into Japanese to produce a version that was semantically and conceptually as close as possible to the original questionnaire. Translation was carried out by two qualified independent linguistic translators; both are native speakers of Japanese and proficient in English. Back translation from Japanese into English was then carried out by another translator, who is a native speaker of English and proficient in Japanese. The back translation form was sent to the original author. Inconsistencies were resolved after repeated discussion among the original author, the English translator and the Japanese investigators and a final version was generated. According to the MMAS-8 score (range 0–8), adherence was defined as high (score 8), medium (score 6 to < 8) or low (score < 6). The proportions and frequencies for categorical variables were calculated, while means and SDs were calculated for continuous variables. The characteristics of the whole sample and of the groups with different levels of adherence in terms of the MMAS-8 score are presented. The v-test for categorical variables or ANOVA for continuous variables was used to evaluate the differences in the study variables among the three adherence groups. Internal consistency was assessed using Cronbach’s a. An acceptable Cronbach’s a value is considered to be ≥ 0 7. Known group validity was assessed through the association of items and MMAS categories using a correlation coefficient and covariance. All analyses were performed using STATA version 9 (StataCorp, College Station, TX, U.S.A.). The significance level was set at P < 0 05. The demographic data of the 3096 patients are summarized in Table 1. The mean age of the subjects was 46 3 years (range 17–85), and 50 4% were male. Among the 3096 participants, 1984 took oral medication and 2763 were treated with topical medication. The mean adherence scores by MMAS-8 were 4 8 for oral and 4 3 for topical medication. The reliability scores (Cronbach’s a) were 0 710 for oral MMAS-8 and 0 715 for topical MMAS-8, which demonstrates the high reliability of the Japanese version of MMAS-8. Adherence levels were compared by the type of medication (oral and topical) (Table 2). The percentages of high, medium and low adherence were 9 5%, 24 2% and 66 3% for oral medication, and 6 9%, 17 7% and 75 5% for topical medication, respectively. The overall adherence status was significantly better for oral medication than for topical medication (Table 2). As shown in Table 3, the adherence to oral medication was significantly associated with age, sex, alcohol consumption, disease classification, frequency of hospital visits, experience of drug effectiveness and overall satisfaction with treatment. Lower adherence was found in younger subjects, female patients, heavier drinkers, cases of atopic dermatitis, those who visited their hospitals less than once per half year or at an unknown frequency, those who had not experienced drug effectiveness and those who were not satisfied with their