Depression is twice as likely to occur in individuals with diabetes mellitus (DM) compared with apparently healthy controls. (1) Prevalence rates vary from 11% to 60%. Higher rates are observed depending on study setting (clinical v. community), assessment tool (self-report questionnaire v. diagnostic tool) and design (uncontrolled v. controlled). (1,2) Depression negatively affects quality of life, (3,4) treatment outcome (5) and medication adherence (6) of patients with DM. Female gender, low socioeconomic class and the presence of other physical illnesses are associated with an increased likelihood of depression in patients with diabetes. (2,7)
In Nigeria, crude prevalence estimates for DM are about 7%; with an estimated 10 million people suffering from the disease. (8) The prevalence in sub-Saharan Africa is expected possibly to triple by 2030, (9) making it a cause for concern of not only health professionals but also policy makers as they initiate strategies to tackle it. Studies enumerating the prevalence of depression among patients with DM in Nigeria, not to mention sub-Saharan Africa, are few. (3,10-12) Studies employing the use of rating scales (10,11) or diagnostic instruments (3,12) have been limited by small sample sizes.
Depression is still largely unrecognised by physicians managing patients with DM. We aimed to determine the prevalence of depression among patients with DM in Nigeria employing a moderate sample. Also, we sought to determine the psychosocial impact of the disease in a developing country.
Materials and methods
Study setting and participants
The study was conducted at the Endocrinology Clinic of the University of Benin Teaching Hospital (UBTH), Benin City, Nigeria, from March to May 2009. The UBTH is a tertiary referral health care facility that provides specialist endocrinology services to a population of approximately 2.5 million people. Patients (who comprised the index group) were aged between 20 and 64 years, had been diagnosed with DM according to World Health Organization (WHO) criteria for at least 1 year, and were without a co-morbid illness that impaired their ability to understand the nature and purpose of the study. A control group (without a history of DM) matched for age ([+ or -]2 years), sex and educational status were recruited from the staff of three local government areas (Ikpoba-Okha, Oredo and Egor) that comprise the areas of Benin City where most of the patients resided.
We administered the following three documents:
* A socio-demographic questionnaire designed by the authors to capture socio-demographic variables such as age, sex, and marital, employment and educational status. In the index group, clinical details such as type of diabetes, duration of illness, modality of treatment and presence of other physical co-morbidities were either extracted or corroborated from patient records.
* The depression module of the Schedule for the Clinical Assessment in Neuropsychiatry (SCAN) (13) to diagnose depression. Recorded data were entered into a computer algorithm that generated a diagnosis according to the International Classification of Diseases (ICD-10) criteria. The SCAN has good psychometric properties and has been used in populations in general hospital and psychiatric settings in Nigeria. (14)
* The Beck Depression Inventory (BDI), (15) a 21-item self-report questionnaire for the measurement of depression and its severity. Each item has a score-range of 0-3; item scores are added to determine the intensity of depression. A minimum total score of 10 is required to identify subjects with significant symptoms. A score range of 10-18 indicates mild/moderate depression; 19-29 moderate/severe; and 30-63 extremely severe depression. The BDI has been standardised and widely used in Nigeria. (15)
The SCAN and the BDI were translated into pidgin English, which is the lingua franca in the cosmopolitan city of Benin, using the method of back translation. …