چکیده (انگلیسی):

Background: Statistically significant results of medical intervention trials are not always clinically meaningful.
We sought to estimate the minimal clinically important difference (MCID) (the smallest change in a given endpoint
that is meaningful to a patient) during seasonal alteration of Japanese cedarcypress pollinosis (JCCP).
Methods: Results of a double-blinded, placebo-controlled trial of JCCP patients conducted between 2008 and
2010 were analyzed using an anchor-based method in which a face scale for Japanese rhinoconjunctivitis
quality-of-life questionnaire (JRQLQ) was set as an anchor. MICDs were calculated as changes of average
scores, including those for naso-ocular symptoms with 5 items in diary cards (T5SS), naso-ocular symptoms
with 6 items (T6SS) and QOL with 17 items on the JRQLQ when face scale scores either improved or deteriorated
by one point.
Results: In 2009 and 2010, 3,698 and 374, respectively, grainscm2 of pollens were dispersed. The MCIDs for
T5SS in 2009 and 2010 were 1.426 (0.285 per item) and 1.441 (0.288), respectively. The MCIDs for T6SS
were 4.115 (0.686) and 3.183 (0.531) in 2009 and 2010, respectively. The MCIDs for QOL were 10.469 (0.616)
and 6.026 (0.354) in 2009 and 2010, respectively.
Conclusions: For T5SS in the diary, T6SS and QOL in JRQLQ, unit differences of 1.5 (0.3 per item), 3.6 (0.6)
and 8.2 (0.5), respectively, were considered clinically meaningful by JCCP patients. The MCID for symptoms
recorded in the diary was stable irrespective of the dispersed pollen level.