title: Standard error of measurement as a valid alternative to minimally important difference for evaluating the magnitude of changes in patient-reported outcomes measures.
abstract: OBJECTIVE
  To assess the degree of agreement between standard error of measurement (SEM) and minimally important difference (MID) criteria to evaluate the magnitude of the change caused by a medical intervention.
  
  
  METHODS
  Data were obtained from a cohort of 603 patients with neuropathic pain undergoing analgesic treatment with gabapentin who completed four health scales: Medical Outcomes Study Sleep Scale, Sheehan Disability Scale, Covi Anxiety Scale, and Raskin Depression scale. After calculating MID and SEM values for all scales, patients were classified into three categories: improvement, no change, and worsening. Agreement between the two criteria was assessed using Cohen's kappa index of agreement and Kendall's tau-b linear correlation coefficient.
  
  
  RESULTS
  The 1 SEM criterion showed the highest agreement (kappa=0.68-1.00) and correlation (tau-b=0.75-1.00) with the MID criterion. Sensitivity analysis performed in gabapentin responders and nonresponders confirmed the results of the main analysis.
  
  
  CONCLUSIONS
  The 1 SEM criterion is a valid alternative to the MID criterion to evaluate the magnitude of the change produced in patient-reported health outcomes measures.
authors.affiliation: Department of Pharmacoeconomics and Health Outcomes Research, Medical Unit, Pfizer Spain. javier.rejas@pfizer.com
authors.forename: Javier
authors.initials: J
authors.lastname: Rejas
authors.forename: Antonio
authors.initials: A
authors.lastname: Pardo
authors.forename: Miguel Angel
authors.initials: MA
authors.lastname: Ruiz
mesh_terms: D000588:Amines / Q000627:therapeutic use; D000700:Analgesics / Q000627:therapeutic use; D015331:Cohort Studies; D003509:Cyclohexanecarboxylic Acids / Q000627:therapeutic use; D003627:Data Interpretation, Statistical; D000077206:Gabapentin; D006801:Humans; D010146:Pain / Q000188:drug therapy; D017060:Patient Satisfaction / Q000706:statistics & numerical data*; D016896:Treatment Outcome; D005680:gamma-Aminobutyric Acid / Q000627:therapeutic use
chemical_list: D000588:Amines; D000700:Analgesics; D003509:Cyclohexanecarboxylic Acids; D005680:gamma-Aminobutyric Acid; D000077206:Gabapentin