Validation of the General Medication Adherence Scale in Saudi Patients With Chronic Diseases

Abstract

Objective: The aim was to validate the General Medication Adherence Scale (GMAS) (English version) in Saudi patients with chronic disease.Methods: A month-long study was conducted in the out-patient department of tertiary care hospitals in three cities of Saudi Arabia that collected data from a randomized sample of Saudi patients with chronic disease. The study aimed to achieve an item-to-subject ratio greater than 1:10. Factor analyses were conducted and fit indices calculated. Convergent, discriminant, known group, and concurrent validities were analysed. Internal consistency was determined using test-retest reliability using Cronbach's alpha (α), McDonald's coefficient omega (ω t ), and Pearson's correlation coefficient (ρ). Sensitivity analysis was conducted. Data were analysed through Statistical Package for Social Sciences (SPSS) version 23. The study was ethically approved (i.e., IRB-129-26/6/1439). Results:The survey gathered responses from 171 patients with a response rate of 85.5%. An item-to-subject ratio of 1:15 was achieved. Factor analysis revealed a threefactor structure with acceptable fit indices (i.e., normed fit index (NFI) = 0.93, Tucker-Lewis index (TLI) = 0.99, and comparative fit index (CFI) = 0.99), i.e., greater than 0.9. The value of root mean square error of approximation (RMSEA) was 0.01, i.e., less than 0.08. The tool established construct validity, i.e., convergent and discriminant validities. Known group and concurrent validities were also established. An α value of 0.74 and ω t value of 0.92 were reported. Test-retest reliability ρ = 0.82, p < 0.001. The tool had high sensitivity (>75%) and specificity (>80%). Conclusion:The GMAS-English was successfully validated in Saudi patients with chronic disease.

Validation of the General Medication Adherence Scale in Pakistani Patients With Rheumatoid Arthritis

“…Factor analyses revealed a 3-factor structure ( Figure 1) with satisfactory fit indices. This finding was in line with previous validation studies of GMAS in Pakistani and Saudi patients (Naqvi et al, 2018b;Naqvi et al, 2019a;Naqvi et al, 2019c). According to Osborne and Costello, a factor with less than three items is generally weak and unstable, especially when the sample size is relatively small (Osborne and Costello, 2005).…”

Translation and validation of the Arabic version of the General Medication Adherence Scale (GMAS) in Saudi patients with chronic illnesses

“…Based on available literature, a ratio of 1:5 up to 1:20 could be used for such studies ( Osborne and Costello, 2004 ). We selected the maximum ratio of 1:20 based on methodology of study that validated the English version of GMAS in this population ( Naqvi et al, 2019b ). Henceforth, a ratio of 1:20 implied that a sample of 220 patients was needed.…”

“…A novel scale termed as the General Medication Adherence Scale (GMAS) was developed and validated in Urdu and English languages in Pakistan; a country with similar culture as Saudi Arabia ( Naqvi et al, 2018 , Naqvi et al, 2019a ). The English version of the scale has already been validated in Saudi patients ( Naqvi et al, 2019b ). However, an Arabic version of the scale is needed to document adherence to medications from a representative population.…”

Association of Disease Knowledge and Medication Adherence Among Out-Patients With Type 2 Diabetes Mellitus in Khobar, Saudi Arabia

“…The research instruments used for evaluation of patient' disease knowledge and medication adherence were the Arabic versions of the Revised Diabetes Knowledge Questionnaire (DKT) and, the General Medication Adherence Scale (GMAS) respectively (Collins et al, 2011;Alhaiti et al, 2016;Fitzgerald et al, 2016;Naqvi et al, 2018;Naqvi and Hassali, 2019;Naqvi et al, 2019a;Naqvi et al, 2019b). The Arabic version of the Revised Diabetes Knowledge Questionnaire (DKT-2) is a 23-item questionnaire containing multiple choice questions (MCQs) to assess the knowledge of diabetes mellitus.…”

“…The scale measures adherence to medications considering patient's behaviors, comorbidities and out-of-pocket expenditures. Each option awards a score and sum of all individual scores yields a patient's adherence to medication (Naqvi et al, 2018;Naqvi et al, 2019a;Naqvi et al, 2019b).…”