Al-Maskari et al. BMC Public Health 2010, 10:679 http://www.biomedcentral.com/1471-2458/10/679 size of 625 was calculated and approached, out of whom 513 (82%) agreed to enrol, of whom 150 (29.3%) patients were enrolled from the two diabetics clinics of the two hospitals. The study was approved by the Ethics Com- mittee of the Faculty of Medicine and Health Sciences of the UAE University. 3. Data collection and definitions Although a vast majority of DM patients receive regular treatment at primary health care clinics in Al-Ain dis- trict, the current system of primary medical care in Al- Ain is not based on continuity of care and accountabil- ity but rather on rapid access without appointment to any physician available. Chronic disease clinics that have been recently implemented in three primary centres may have an impact on quality of care but due to logis- tical reasons (data completeness and accessibility), only patients attending outpatient clinics at Al- Ain and Tawam hospitals were included in the study. Consenting hospital patients were asked to complete an interviewer administered questionnaire on frequency of initial and follow up visits, hospital admissions and all medical support causally related to DM management during the past 12 months to validate hospital and clinic data. Clinical data for patients were retrieved from their medical records at the two hospitals. It was not always possible to distinguish clearly between types 1 and 2 diabetes from the medical records alone and for that we opted to use the terms “insulin treated diabetes”, and “non-insulin treated dia- betes” to classify DM patients. The following sequelae of chronic diabetic cardiovascular complications were con- sidered for analysis: (1) Macro-vascular complications: acute myocardial infarction, angina pectoris, stroke, and non-traumatic amputation and foot ulcers; (2) Micro- vascular complications: various levels of nephropathy (i. e. microalbuminuria, clinical proteinuria and chronic renal failure), retinopathy (i.e. background and prolifera- tive retinopathy, macular edema, cataract and blindness) and peripheral neuropathy. The diagnosis of various chronic complications of DM was based on medical records. To assign costs to the care received by patients, the study used the official list of charges/rates for patients not covered by health insurance at the time (the official rates for non health card holders). Those charges/prices were allegedly based on approximate real costs; i.e. the rates which, if charged to all individual patients, would have covered the actual costs incurred to provide these services without significant profits and/or subsidies. The average unit costs per patient were estimated by using expert opinion (consultants and doctors from participat- ing hospitals) to distinguish and verify from the files of individuals patients, health care consumption by Page 3 of 10 individual patients (including accommodation, pharma- ceuticals, laboratory, nursing costs etc), likely received for DM related conditions and that for other- unrelated- reasons. Costs for DM related conditions were then assigned by calculating the charges that non-card holders would have paid for such health care services. These unit costs were then extrapolated to all patients whether he/she had actually paid for them or not (UAE nationals are automatically insured against all medical costs). To comprehend the combined cost impact of DM complication on health care resources, the study calculated and compared the treatment costs of DM patients without complications to those of patients with micorvascualr complications, those with macrovasualr complications and those with both, macro and micro- vascualr complications. 4. Statistical Analysis Data entry and analysis was performed using the statisti- cal software package (SPSS version 13). Cost estimates are presented as point estimates with associated stan- dard deviations. The study used conventional methods of statistical inference and hypothesis testing. The Chi- square test and the t-test were used, where appropriate, to test for significance (p < 0.05 is considered statisti- cally significant). Linear regression, with logarithmically transformed costs as the dependent variable, was used to estimate the simultaneous effect of various patient characteristics on costs. A logarithmical transformation was used, as patients characteristics were believed to act multiplicatively on costs rather than additively. As ran- dom selection of patients attending the clinic may lead to size-biased sampling (those attending the clinic more frequently are oversampled), the number of visits of a patient to the clinic was treated as a “design” variable and either used (inversely) as a weighting factor, or included as a covariate in our regression/covariance analyses. Results 1. Demographic characteristics A total of 150 DM patients were enrolled; 63% from Tawam hospital and 37% from Al-Ain hospital. Of the total sample 67% were males, 48% were UAE nationals, 7% were citizens from other Gulf (GCC) countries, 30% were resident Arabs from other countries and 15% were expatriate Asians living and working in the UAE. Thirty three percent were above sixty years. The mean age was 55.6 years (SD: 13.3: range 14-85) and 46% were illiter- ate (Table 1). 2. Clinical History of the Sample Population Fifty-seven percent of the sample populations were ‘non insulin treated’ DM patients. Forty- percent had the