THE IMPACT OF MAJOR MENTAL ILLNESS ON QUALITY OF CARE IN PEOPLE WITH TYPE 2 DIABETES IN SCOTLAND: AN ANALYSIS OF ROUTINELY COLLECTED HEALTH DATA

Background Recent evidence from some countries suggests that people with a mental health condition receive poorer type 2 diabetes mellitus (T2DM) care than people without a mental health condition. We aimed to investigate whether history of a major mental illness affects quality of care in people with T2DM in Scotland. Methods We identified adults diagnosed with T2DM between 2007 and 2015 from a 2016 extract of Scotland’s national diabetes register (the Scottish Care Information (SCI) – Diabetes database). We used International Classification of Disease codes to identify history of mental illness from pseudonymously linked Scottish psychiatric and acute hospital admission records. Retinopathy screening and HbA1c measurement within the first year post T2DM diagnosis were determined from the diabetes register. Using logistic regression analysis, we obtained odds ratios (ORs) for receipt of both tests for people with a history of schizophrenia, bipolar disorder or depression in hospital records, compared to those without a history of mental illness in hospital records. Results We included 129,028 people with T2DM. Of these, 1,457 (1.1%) had schizophrenia, 653 (0.5%) had bipolar disorder and 4,132 (3.2%) had depression. Within the first year post T2DM diagnosis, 84.1% of the cohort received retinopathy screening and 92.5% received HbA1c measurement. Both retinopathy screening and HbA1c measurement were received by 81.3% of people without a history of mental illness compared to 75.0% of people with schizophrenia, 77.5% of people with bipolar disorder and 77.7% of people with depression. After adjusting for health board, year, age, sex, area-based deprivation, ethnicity and comorbidities, the odds of receiving both tests were lower in people with schizophrenia (OR 0.77, 95% confidence interval (CI) 0.68, 0.87), bipolar disorder (OR 0.78, 95% CI 0.65, 0.94) and depression (OR 0.82, 95% CI 0.76, 0.89) compared to those without a history of mental illness. These differences were driven by lower percentages of retinopathy screening amongst people with schizophrenia, bipolar disorder or depression; proportions with HbA1c measurement were similar across all groups. Conclusion Compared to people without a history of mental illness, people with schizophrenia, bipolar disorder or depression are less likely to receive diabetic retinopathy screening within the first year post T2DM diagnosis. Such discrepancies in care may contribute to poorer T2DM outcomes amongst people with a major mental illness. Further work will investigate whether discrepancies in care persist beyond the first year post T2DM diagnosis and how discrepancies in care have evolved over time.