PMID- 34753761
OWN - NLM
STAT- MEDLINE
DCOM- 20211206
LR  - 20211214
IS  - 2044-6055 (Electronic)
IS  - 2044-6055 (Linking)
VI  - 11
IP  - 11
DP  - 2021 Nov 9
TI  - Minimal clinically important difference in means in vulnerable populations: 
      challenges and solutions.
PG  - e052338
LID - 10.1136/bmjopen-2021-052338 [doi]
LID - e052338
AB  - INTRODUCTION AND MOTIVATION: Many health studies measure a continuous outcome and 
      compare means between groups. Since means for biological data are often difficult 
      to interpret clinically, it is common to dichotomise using a cut-point and 
      present the 'percentage abnormal' alongside or in place of means. Examples 
      include birthweight where 'abnormal' is defined as <2500 g (low birthweight), 
      systolic blood pressure with abnormal defined as >140 mm Hg (high blood pressure) 
      and lung function with varying definitions of the 'limit of normal'. In 
      vulnerable populations with low means, for example, birthweight in a population 
      of preterm babies, a given difference in means between two groups will represent 
      a larger difference in the percentage with low birthweight than in a general 
      population of babies where most will be full term. Thus, in general, the 
      difference in percentage of patients with abnormal values for a given difference 
      in means varies according to the reference population's mean value. This 
      phenomenon leads to challenges in interpreting differences in means in vulnerable 
      populations and in defining an outcome-specific minimal clinically important 
      difference (MCID) in means since the proportion abnormal, which is useful in 
      interpreting means, is not constant-it varies with the population mean. This has 
      relevance for study power calculations and data analyses in vulnerable 
      populations where a small observed difference in means may be difficult to 
      interpret clinically and may be disregarded, even if associated with a relatively 
      large difference in percentage abnormal which is clinically relevant. METHODS: To 
      address these issues, we suggest both difference in means and difference in 
      percentage (proportion) abnormal are considered when choosing the MCID, and that 
      both means and percentages abnormal are reported when analysing the data. 
      CONCLUSIONS: We describe a distributional approach to analyse proportions 
      classified as abnormal that avoids the usual loss of precision and power 
      associated with dichotomisation.
CI  - (c) Author(s) (or their employer(s)) 2021. Re-use permitted under CC BY-NC. No 
      commercial re-use. See rights and permissions. Published by BMJ.
FAU - Peacock, Janet L
AU  - Peacock JL
AUID- ORCID: 0000-0002-0310-2518
AD  - Department of Epidemiology, Geisel School of Medicine at Dartmouth, Hanover, New 
      Hampshire, USA janet.peacock@dartmouth.edu.
FAU - Lo, Jessica
AU  - Lo J
AD  - Centre for Healthy Brain Ageing, University of New South Wales, Sydney, New South 
      Wales, Australia.
FAU - Rees, Judith R
AU  - Rees JR
AD  - Department of Epidemiology, Geisel School of Medicine at Dartmouth, Hanover, New 
      Hampshire, USA.
FAU - Sauzet, Odile
AU  - Sauzet O
AUID- ORCID: 0000-0002-1029-8846
AD  - Epidemiology and International Public Health, Bielefeld School of Public Health, 
      Bielefeld University, Bielefeld, Germany.
LA  - eng
PT  - Journal Article
PT  - Review
DEP - 20211109
PL  - England
TA  - BMJ Open
JT  - BMJ open
JID - 101552874
SB  - IM
MH  - Birth Weight
MH  - Humans
MH  - *Infant, Low Birth Weight
MH  - Infant, Newborn
MH  - *Minimal Clinically Important Difference
PMC - PMC8578978
OTO - NOTNLM
OT  - epidemiology
OT  - public health
OT  - statistics & research methods
COIS- Competing interests: None declared.
EDAT- 2021/11/11 06:00
MHDA- 2021/12/15 06:00
PMCR- 2021/11/09
CRDT- 2021/11/10 05:42
PHST- 2021/11/10 05:42 [entrez]
PHST- 2021/11/11 06:00 [pubmed]
PHST- 2021/12/15 06:00 [medline]
PHST- 2021/11/09 00:00 [pmc-release]
AID - bmjopen-2021-052338 [pii]
AID - 10.1136/bmjopen-2021-052338 [doi]
PST - epublish
SO  - BMJ Open. 2021 Nov 9;11(11):e052338. doi: 10.1136/bmjopen-2021-052338.