Table 2

Results of logistic regression and factor analysis of the PSQ-SRDB

Symptom categoryItemLogistic regression*Factor analysis†
ORP valuesNew factorLoading
Factor 1: breathingA2: snores more than half the time15.956<0.001Breathing0.596
A3: always snores12.042<0.001Breathing0.723
A4: snores loudly14.027<0.001Breathing0.707
A5: heavy breathing10.628<0.001Breathing0.716
A6: trouble breathing27.018<0.001Breathing0.613
A7: observed apnoeas11.325<0.001Breathing0.420
A24: mouth open during day6.568<0.001Morning0.496
A25: dry mouth on awakening4.73<0.001Morning0.741
B7: morning headache6.453<0.001Morning0.673
Factor 2: sleepinessB2: problem with sleepiness6.849<0.001Sleepiness0.809
B4: sleepy as per the teacher9.328<0.001Sleepiness0.809
Factor 3: behaviourC3: does not listen8.221<0.001Behaviour0.653
C5: difficulty in organising6.235<0.001Behaviour0.475
C8: easily distracted7.428<0.001Behaviour0.596
C10: fidgets11.173<0.001Behaviour0.617
C14: on the go7.234<0.001Behaviour0.666
C18: interrupts7.426<0.001Behaviour0.654
Factor 4: other symptomsA32: nocturnal enuresis2.761<0.001Others0.660
B1: unrefreshed in morning11.942<0.001Morning0.461
B6: hard to wake up7.142<0.001Sleepiness0.337
B9: delayed growth0.998Others0.199
B22: obesity2.324<0.001Others0.656
  • The number of the items was arranged in accordance with the original questionnaire.12

  • *Logistic regression was used to measure the strength of association between the items and the suspected SDB.

  • †Factor analysis was conducted by the principal components method with varimax rotation.

  • PSQ-SRDB, Pediatric Sleep Questionnaire-Sleep-Related Breathing Disorder; SDB, sleep-disordered breathing.