title: A Markov model to evaluate hospital readmission.
abstract: BACKGROUND
  The analysis of non-fatal recurring events is frequently found in studies on chronic-degenerative diseases. The aim of this paper is to estimate the probability of readmission of patients with Chronic Obstructive Pulmonary Disease (COPD) or with Respiratory Failure (RF).
  
  
  METHODS
  The Repeated hospital admissions of a patient are considered as a Markov Chain. The transitions between the states are estimated using the Nelson-Aalen estimator. The analysis was carried out using the Puglia Region hospital patient discharge database for the years 1998-2005. Patients were selected on the basis of first admission between 01/01/2001 and 31/12/2005 with ICD-9-CM code of COPD or RF as principal and/or secondary diagnosis. For those selected two possible transitions were considered in the case they had the second and third admission with an ICD-9-CM code of COPD or RF as principal diagnosis.
  
  
  RESULTS
  The probability of readmission is increased in patients with a diagnosis of RF (OR = 1.618 in the first transition and 1.279 in the second) and also in those with a diagnosis of COPD or RF as the principal diagnosis at first admission (OR = 1.615 in the first transition and 1.193 in the second). The clinical gravity and the ward from which they were discharged did not significantly influence the probability of readmission.
  
  
  CONCLUSIONS
  The time to readmission depends on the gravity of the pathology at onset. In patients with a grave clinical picture, either COPD or Respiratory Failure, when treated and controlled after the first admission, they become minor problems and they are indicated among secondary diagnoses in any further admission.
authors.affiliation: Department of Biomedical Science and Human Oncology, Chair of Medical Statistics, University of Bari, Italy. nicolabartolomeo@virgilio.it
authors.forename: Nicola
authors.initials: N
authors.lastname: Bartolomeo
authors.forename: Paolo
authors.initials: P
authors.lastname: Trerotoli
authors.forename: Annamaria
authors.initials: A
authors.lastname: Moretti
authors.forename: Gabriella
authors.initials: G
authors.lastname: Serio
mesh_terms: D000368:Aged; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D038801:International Classification of Diseases; D007558:Italy; D008297:Male; D008390:Markov Chains; D008875:Middle Aged; D010359:Patient Readmission / Q000706:statistics & numerical data*; D016016:Proportional Hazards Models; D029424:Pulmonary Disease, Chronic Obstructive; D012008:Recurrence; D012131:Respiratory Insufficiency; D018570:Risk Assessment