Chapter 4 Comorbidities and current smoking status amongst patients starting renal replacement therapy in England, Wales and Northern Ireland from 2009 to 2010.

INTRODUCTION: Comorbidities are an important determinant of survival for patients requiring renal replacement therapy (RRT) and influence other care processes such as dialysis access formation and transplant wait-listing. The prevalence of comorbidities in incident RRT patients changes with age and varies between ethnic groups. This study describes these associations and the independent effect of comorbidities on outcomes.

METHODS: Incident patients reported to the UK Renal Registry (UKRR) with comorbidity data in 2009 and 2010 (n = 6,130) were included in analyses exploring the association of comorbidities with patient demographics, treatment modality, haemoglobin and renal function at start of RRT. For analyses examining association between comorbidities and survival, adult patients starting RRT between 2005 and 2010 in centres reporting to the UKRR with comorbidity data (n = 17,184) were included. The relationship between comorbidities and mortality at 90 days and one year after 90 days from start of RRT were explored using Cox regression.

RESULTS: Completeness of comorbidity data was 49.1% in 2010 compared with 48.9% in 2005. Of patients with data, 55.4% had one or more comorbidities. Diabetes mellitus and ischaemic heart disease were the most common conditions, observed in 33.3% and 21.1% of patients respectively. 13.2% of incident RRT patients in the 2-year period were recorded as current smokers. The prevalence of comorbidity increased with increasing age across all ethnic groups. In multivariable survival analysis, malignancy and the presence of ischaemic/neuropathic ulcers were strong independent predictors of poor survival at 1 year after 90 days from the start of RRT in patients <65 years.

CONCLUSION: Differences in prevalence rates of comorbid illnesses in incident RRT patients may reflect variation in access to health care or competing risk prior to commencing treatment. The generalisability of these analyses continues to be limited by poor data completeness.