A cross-sectional study in which the EQ-5D-3L instrument was used to assess the health related quality of life of a sample of patients with T2DM was conducted. The patients were recruited from two teaching hospitals in Anambra state, south east Nigeria, namely: Nnamdi Azikiwe University Teaching Hospital (NAUTH) and Anambra State University Teaching Hospital Amaku (ASUTH). Both hospitals are the only tertiary hospitals in Anambra State, which is one of 36 states in the south-eastern part of Nigeria. Nnamdi Azikiwe University Teaching Hospital (NAUTH) is a 355 bed multi annex complex, providing both specialized and comprehensive medical care services. ASUTH is also a government owned, newly upgraded tertiary health institution, with a 200 bed capacity. Only patients diagnosed with diabetes on the ICD10-E11 i.e., T2DM, and who could read and understand English were included. Severely ill patients as well as those who were in hospital for a follow-up visit were included in the study.
The EQ-5D instrument, which is described more fully in a separate paper (13), is a standardised instrument for measuring health outcomes. The instrument provides a simple descriptive profile and a single index value for health status. It is primarily designed for self-completion by respondents and is ideally suited for use in postal surveys, in clinics and for face-to-face interviews. It is cognitively simple, taking only a few minutes to complete. The instrument has five dimensions which are mobility; self-care; usual activities; pain/discomfort and anxiety/depression. Each dimension has three levels (no problems, some problems, and major problems) which together define 243 health states (3 to the power of 5 gives the 243 possible combinations). The instrument also has a number of country-specific scoring functions available, which allow for the determination of utilities specific to certain settings. The study adopted a time trade off (TTO) method of health utility measurement as applied in Zimbabwe , which is the only African country with country-specific scoring functions. The questionnaire covered the patients’ basic demographic details and clinical information and also included a general health visual analogue scale (EQ VAS). Using a vertical 20 cm graduated line, patients reported their current level of health state by placing a mark on the line. The scale is anchored with 0 to represent the worst imaginable health state, and 100 to represent the best imaginable health state.
Data administration and collection
Researchers distributed the self-administered questionnaires to the patients while they were waiting to see a doctor in the diabetic clinic of the two tertiary hospitals. Where necessary, the researchers assisted the patients or clarified any queries about the questionnaire. The questionnaires were collected after the patients had completed them. The number of complications (as specified by ICD 10) and co-morbidites (none diabetes mellitus related illness) were afterwards retrieved from clinical notes. The study was conducted between May and August 2014. At NAUTH, this was done on pre-set diabetic clinic days. ASUTH had no special diabetic clinic days and so the survey was conducted on random days.
This study was approved by the Ethics committee of Nnamdi Azikiwe University Teaching Hospital Nnewi, Nigeria. All procedures were carried out according to the study protocol approved by the Ethics Committee. Oral informed consent was obtained from each patient. The information about participants’ identity was not included with the other data and only the principal investigator had access to this information. No reference to the participant’s identity was made at any stage during data analysis.
Health profiles were presented in frequencies stratified by age group. EQ VAS score and EQ-5D index were presented as mean ± standard deviation. In order to establish construct validity, a priori hypotheses on their relevance in T2DM and their ability to test the performance of the EQ VAS score and EQ-5D index were postulated. We hypothesized that (1) patients with more complications will have poor utility, (2) patients with more morbidity will have poor utility, (3) utility will decease with increasing age; and (4) gender will have no effect on the utility of T2DM. The dependent variables were EQ VAS score and EQ-5D index and both were characterised as continuous variables. Independent variables were age, gender, level of education, number of diabetic complications and number of co-morbidities. Age was characterised as continuous variable, gender was treated as binary data while level of education, number of diabetic complication and number of co-morbidities were treated as categorical data. Using the stepwise method, a multiple regression was conducted to examine if the hypothesized independent variables predicted EQ VAS and EQ-5D index. Data analysis was conducted with SPSS 14.0® (Chicago, Illinois, USA). All hypotheses tested were two-tailed, with significance set at p < 0.05.