title: Predicting patient 'cost blooms' in Denmark: a longitudinal population-based study.
abstract: To compare the ability of standard versus enhanced models to predict future high-cost patients, especially those who move from a lower to the upper decile of per capita healthcare expenditures within 1 year-that is, 'cost bloomers'.
  
  
  
  We developed alternative models to predict being in the upper decile of healthcare expenditures in year 2 of a sample, based on data from year 1. Our 6 alternative models ranged from a standard cost-prediction model with 4 variables (ie, traditional model features), to our largest enhanced model with 1053 non-traditional model features. To quantify any increases in predictive power that enhanced models achieved over standard tools, we compared the prospective predictive performance of each model.
  
  
  
  We used the population of Western Denmark between 2004 and 2011 (2 146 801 individuals) to predict future high-cost patients and characterise high-cost patient subgroups. Using the most recent 2-year period (2010-2011) for model evaluation, our whole-population model used a cohort of 1 557 950 individuals with a full year of active residency in year 1 (2010). Our cost-bloom model excluded the 155 795 individuals who were already high cost at the population level in year 1, resulting in 1 402 155 individuals for prediction of cost bloomers in year 2 (2011).
  
  
  
  Using unseen data from a future year, we evaluated each model's prospective predictive performance by calculating the ratio of predicted high-cost patient expenditures to the actual high-cost patient expenditures in Year 2-that is, cost capture.
  
  
  
  Our best enhanced model achieved a 21% and 30% improvement in cost capture over a standard diagnosis-based model for predicting population-level high-cost patients and cost bloomers, respectively.
  
  
  
  In combination with modern statistical learning methods for analysing large data sets, models enhanced with a large and diverse set of features led to better performance-especially for predicting future cost bloomers.
authors.affiliation: Department of Medicine, Stanford University School of Medicine, Stanford, California, USA.
authors.forename: Suzanne
authors.initials: S
authors.lastname: Tamang
authors.affiliation: Department of Medicine, Stanford University School of Medicine, Stanford, California, USA.
authors.forename: Arnold
authors.initials: A
authors.lastname: Milstein
authors.affiliation: Department of Clinical Epidemiology, Aarhus University, Aarhus, Denmark.
authors.forename: Henrik Toft
authors.initials: HT
authors.lastname: Sørensen
authors.affiliation: Department of Clinical Epidemiology, Aarhus University, Aarhus, Denmark.
authors.forename: Lars
authors.initials: L
authors.lastname: Pedersen
authors.affiliation: Department of Statistics, Stanford University, Stanford, California, USA.
authors.forename: Lester
authors.initials: L
authors.lastname: Mackey
authors.affiliation: Department of Statistics, Stanford University, Stanford, California, USA.
authors.forename: Jean-Raymond
authors.initials: JR
authors.lastname: Betterton
authors.affiliation: Department of Statistics, Stanford University, Stanford, California, USA.
authors.forename: Lucas
authors.initials: L
authors.lastname: Janson
authors.affiliation: Department of Medicine, Stanford University School of Medicine, Stanford, California, USA.
authors.forename: Nigam
authors.initials: N
authors.lastname: Shah
mesh_terms: D003718:Denmark / Q000453:epidemiology; D005260:Female; D017048:Health Care Costs / Q000706:statistics & numerical data; D019538:Health Care Surveys; D005102:Health Expenditures / Q000706:statistics & numerical data; D006801:Humans; D007348:Insurance, Health / Q000706:statistics & numerical data*; D008137:Longitudinal Studies; D008297:Male; D017059:Models, Econometric; D020379:Risk Adjustment; D014600:Utilization Review
keywords: high-cost patients; predictive analytics