Reliability and Validity Assessment of the General Medication Adherence Scale among Breast Cancer Patients in Pakistan

Noreen, Daniya; Shakeel, Sadia; Rahim, Najia; Shamim, Sana; Anjum, Fakhsheena; Zehra, Ale; Haider, Ghulam; Shakeel Ahmed, Ayesha

doi:10.31557/APJCP.2026.27.6.2225

Reliability and Validity Assessment of the General Medication Adherence Scale among Breast Cancer Patients in Pakistan

Document Type : Research Articles

Authors

¹ Dow Institute of Medical Technology, Dow University of Health Sciences, Karachi, Pakistan.

² Department of Pharmacy Practice, Faculty of Pharmaceutical Sciences, Dow College of Pharmacy, Dow University of Health Sciences, Karachi, Pakistan.

³ Department of Pharmaceutical Chemistry, Faculty of Pharmaceutical Sciences, Dow College of Pharmacy, Dow University of Health Sciences, Karachi, Pakistan.

⁴ Department of Clinical Oncology, Jinnah Postgraduate Medical Centre, Karachi, Pakistan.

⁵ Institute of Medical Technology, Jinnah Sindh Medical University, Karachi, Pakistan.

10.31557/APJCP.2026.27.6.2225

Abstract

Background: Adherence rates to adjuvant therapy for breast cancer are often suboptimal, which raises the risk of recurrence, lowers survival rates, and increases healthcare expenses. The present study aimed to assess the validity and reliability of the General Medication Adherence Scale (GMAS) in identifying adherence to adjuvant cancer therapy (ACT) in breast cancer patients. Method: A prospective, cross-sectional study was conducted on breast cancer patients using the Urdu version of the GMAS. Reliability was assessed using Cronbach’s alpha (α) and inter-item correlations. The instrument was subjected to principal component factor analysis (PCFA) with varimax rotation. Exploratory factor analysis (EFA) and PCFA were performed using IBM SPSS version 23, while confirmatory factor analysis (CFA) was carried out using IBM AMOS version 25. Results: Cronbach’s alpha of the GMAS was found to be 0.882, confirming that the scale has good reliability. The mean score was significantly different among items ensuring the significance of each item in the GMAS scale (Tukey’s test p< 0.0001; Chi-square=38.825, p< 0.0001). A total of 204 female responses were recorded; the mean age was 41.2±9.5 years. It was observed that n=95 (46.5%) of patients showed partial adherence whereas n=76 (37.2%) patients were highly adherent to ACT. The probability of patients’ adhering to their therapy was greater among those who were employed [OR = 1.95, 95% CI (1.27, 2.62)] and have higher level of education [OR = 2.93, 95% CI (1.39, 4.46)]. The potential reasons for non-adherence were the cost of treatment n=44 (21.5%), adverse effects n=33 (16.1%), depression and emotional stress n=32 (15.6%). Conclusions: The Urdu version of GMAS, validated with good internal reliability, proved to be a feasible and accurate tool for measuring adherence among breast cancer patients.

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