Concurrent validity of the Arabic version of General Medication Adherence Scale using two validated indirect adherences measures in Saudi patients with non-communicable diseases

Purpose: This study aimed to evaluate the concurrent validity of the Arabic version of the General Medication Adherence Scale (GMAS) using two validated scales namely Adherence to Refills and Medications Scale (ARMS) and Medication Adherence Rating Scale (MARS) in Saudi patients with non-communicable diseases. Methods: A cross sectional study was conducted for 2 months in out-patient departments at a tertiary care hospital in Khobar, Saudi Arabia. The study collected data from patients with chronic illnesses through convenience sampling. Pearson correlation (ρ) was conducted to report concurrent validity of GMAS. A correlation coefficient value ≥ 0.5 with p-value < 0.01 was considered threshold for establishing concurrent validity. The study was approved by an ethics committee (IRB-2019–05-002). Results: A total of 406 patients responded to the study. The average age was 42.4 ± 5.94 years, and most patients were females (53.7%), married (70%), graduates (65.3%), employed (39.9%) and, had a monthly family income > SAR 10,000, i.e., USD 2666.2 (56.4%). The mean adherence scores obtained from MARS, ARMS and GMAS were 7.09, 19.9, and 27.4. The correlation (ρ) between GMAS and MARS scores was 0.65, and between GMAS and ARMS scores was −0.79, p < 0.01 for both comparisons. Conclusion: The concurrent validity of GMAS-AR was established in this study that would further substantiate psychometric properties of the scale in this population.