The minimal clinically important difference in allergic rhinitis.
BACKGROUND
When presented with results from clinical measurements or research findings, clinicians must first make an interpretation of their importance, not only in statistical terms, but also the 'clinical importance' given the size of the change observed. To do this, they require an understanding of the relationship between their outcome measures, and the patient's perception of change. The minimal clinically important difference (MCID) illustrates this relationship by calculating the smallest change in a given outcome that is meaningful to a patient. There are few reports of calculated MCIDs in the Rhinology literature.


OBJECTIVE
To calculate MCIDs for common subjective and objective outcome measures in allergic rhinitis (AR).


METHODS
Nine randomized, blinded, placebo-controlled clinical trials in intermittent and persistent AR (pooled subjects, n=204) were analysed using anchor- and distribution-based approaches, applying regression and meta-analysis techniques.


RESULTS
MCIDs were obtained for the Mini Rhinoconjunctivitis Quality of Life Questionnaire: 0.4 units, peak nasal inspiratory flow: 5 L/min and total nasal symptoms score: 0.55 units. Nasal NO measurement changes had no correlation with patient perceptions of benefit.


CONCLUSIONS
Estimates of MCIDs were obtained for common subjective and objective rhinological outcomes. MCIDs can and should be applied by physicians interpreting research findings, as well as researchers reporting their findings. We can then be confident that our changes in practice will be of perceptible benefit to the patient.
Barnes
M L
ML
Asthma & Allergy Research Group, Department of Medicine and Therapeutics, Ninewells Hospital & Medical School, University of Dundee, Scotland, UK. mr.mlbarnes@gmail.com
Vaidyanathan
S
S
Williamson
P A
PA
Lipworth
B J
BJ
D004311:Double-Blind Method; D006801:Humans; D009569:Nitric Oxide / Q000032:analysis; D011788:Quality of Life; D016032:Randomized Controlled Trials as Topic; D012044:Regression Analysis; D012221:Rhinitis, Allergic, Perennial / Q000175:diagnosis* / Q000503:physiopathology / Q000523:psychology*; D012680:Sensitivity and Specificity; D011795:Surveys and Questionnaires; D016896:Treatment Outcome
D009569:Nitric Oxide