title: Predicting hospital costs for patients receiving renal replacement therapy to inform an economic evaluation.
abstract: OBJECTIVE
  To develop a model to predict annual hospital costs for patients with established renal failure, taking into account the effect of patient and treatment characteristics of potential relevance for conducting an economic evaluation, such as age, comorbidities and time on treatment. The analysis focuses on factors leading to variations in inpatient and outpatient costs and excludes fixed costs associated with dialysis, transplant surgery and high cost drugs.
  
  
  METHODS
  Annual costs of inpatient and outpatient hospital episodes for patients starting renal replacement therapy in England were obtained from a large retrospective dataset. Multiple imputation was performed to estimate missing costs due to administrative censoring. Two-part models were developed using logistic regression to first predict the probability of incurring any hospital costs before fitting generalised linear models to estimate the level of cost in patients with positive costs. Separate models were developed to predict inpatient and outpatient costs for each treatment modality.
  
  
  RESULTS
  Data on hospital costs were available for 15,869 incident dialysis patients and 4511 incident transplant patients. The two-part models showed a decreasing trend in costs with increasing number of years on treatment, with the exception of dialysis outpatient costs. Age did not have a consistent effect on hospital costs; however, comorbidities such as diabetes and peripheral vascular disease were strong predictors of higher hospital costs in all four models.
  
  
  CONCLUSIONS
  Analysis of patient-level data can result in a deeper understanding of factors associated with variations in hospital costs and can improve the accuracy with which costs are estimated in the context of economic evaluations.
authors.affiliation: Department of Health Services Research and Policy, London School of Hygiene and Tropical Medicine, 15-17 Tavistock Place, London, WC1H 9SH, UK. bernadette.li@lshtm.ac.uk.
authors.forename: Bernadette
authors.initials: B
authors.lastname: Li
authors.affiliation: Department of Health Services Research and Policy, London School of Hygiene and Tropical Medicine, 15-17 Tavistock Place, London, WC1H 9SH, UK.
authors.forename: John
authors.initials: J
authors.lastname: Cairns
authors.affiliation: Sheffield Kidney Institute, Sheffield, UK.
authors.forename: James
authors.initials: J
authors.lastname: Fotheringham
authors.affiliation: Richard Bright Renal Unit, Southmead Hospital, Bristol, UK.
authors.forename: Rommel
authors.initials: R
authors.lastname: Ravanan
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D015897:Comorbidity; D017281:Cost of Illness; D003362:Cost-Benefit Analysis; D016208:Databases, Factual; D004739:England / Q000453:epidemiology; D005260:Female; D017048:Health Care Costs / Q000706:statistics & numerical data; D017721:Hospital Costs / Q000706:statistics & numerical data; D006801:Humans; D007297:Inpatients; D016030:Kidney Transplantation / Q000191:economics*; D016015:Logistic Models; D008297:Male; D008875:Middle Aged; D009026:Mortality; D010045:Outpatients; D010865:Pilot Projects; D006435:Renal Dialysis / Q000191:economics*; D051436:Renal Insufficiency, Chronic / Q000150:complications / Q000191:economics* / Q000453:epidemiology / Q000628:therapy; D017582:Renal Replacement Therapy / Q000191:economics; D013222:State Medicine
keywords: Established renal failure; Hospital costs; Patient-level data; Regression; Two-part model