Distribution-based estimates of minimal important difference for hospital anxiety and depression scale and impact of event scale-revised in survivors of acute respiratory failure

Gen Hosp Psychiatry. 2016 Sep-Oct:42:32-5. doi: 10.1016/j.genhosppsych.2016.07.004. Epub 2016 Jul 12.


Objective: This study will estimate distribution-based minimal important difference (MID) for the Hospital Anxiety and Depression Scale anxiety (HADS-A) and depression (HADS-D) subscales, and the Impact of Event Scale-Revised (IES-R) in survivors of acute respiratory failure (ARF).

Methods: Secondary analyses of data from two US and three UK studies of ARF survivors (total N=1223). HADS-D and HADS-A were used to assess depression and anxiety symptoms. IES-R assessed post-traumatic stress disorder symptoms. Standard error of measurement, minimal detectable change90, 0.5 standard deviation (S.D.), and 0.2 S.D. were used to estimate MID for the combined sample, by studies, 6- and 12-month follow-ups, country and mental health condition.

Results: Overall, MID estimates converged to 2.0-2.5 for the HADS-A, 1.9-2.3 for the HADS-D and 0.17-0.18 for the IES-R. MID estimates were comparable across studies, follow-up, country and mental health condition.

Conclusion: Among ARF survivors, 2.0-2.5 is a reasonable range for the MID for both HADS subscales, and 0.2 is reasonable for IES-R. Until anchor-based MIDs for these instruments are available, these distribution-based estimates can help researchers plan future studies and interpret the clinical importance of findings in ARF patient populations.

Keywords: Acute respiratory failure; Hospital anxiety and depression scale; Impact of event scale-revised; Minimal important difference.

Publication types

  • Research Support, Non-U.S. Gov't
  • Research Support, N.I.H., Extramural

MeSH terms

  • Adult
  • Anxiety / diagnosis*
  • Data Interpretation, Statistical*
  • Depression / diagnosis*
  • Female
  • Follow-Up Studies
  • Humans
  • Male
  • Middle Aged
  • Psychiatric Status Rating Scales / statistics & numerical data*
  • Respiratory Insufficiency / psychology*
  • Stress Disorders, Post-Traumatic / diagnosis*
  • Survivors / psychology*