Timing of access to secondary healthcare services for diabetes management and lower extremity amputation in people with diabetes: a protocol of a case–control study

BACKGROUND Lower extremity amputation (LEA) is a complication of diabetes and a marker of the quality of diabetes care. Clinical and sociodemographic determinants of LEA in people with diabetes are well known. However, the role of service-related factors has been less well explored. Early referral to secondary healthcare is assumed to prevent the occurrence of LEA. The objective of this study is to investigate a possible association between the timing of patient access to secondary healthcare services for diabetes management, as a key marker of service-related factors, and LEA in patients with diabetes. METHODS/DESIGN This is a case-control study. The source population is people with diabetes. Cases will be people with diabetes who have undergone a first major LEA, identified from the hospital discharge data at each of three regional centres for diabetes care. Controls will be patients with diabetes without LEA admitted to the same centre either electively or as an emergency. Frequency-matching will be applied for gender, type of diabetes, year and centre of LEA. Three controls per case will be selected from the same population as the cases. With a power of 90% to detect OR of 0.4 for an association between 'good quality care' and LEA in people with diabetes, 107 cases and 321 controls are required. Services involved in diabetes management are endocrinology, ophthalmology, renal, cardiology, vascular surgery and podiatry; timing of first contact with any of these services is the main exploratory variable. Using unconditional logistic regression, an association between this exposure and the outcome of major LEA in people with diabetes will be explored, while adjusting for confounders. ETHICS AND DISSEMINATION Ethical approval was granted by the Clinical Research Ethics Committee of the Cork Teaching Hospitals, Ireland. Results will be presented at conferences and published in peer-reviewed journals.