Table 3

Summary of results of studies of circadian variation in measurements of peak expiratory flow (PEF)

Reference no.Number of PEF measurementsOutcome measure usedExposure comparisonResultsp value
35 Not givenNot givenCigarettes smoked in home each day% classified as “bronchially reactive” was 31% in unexposed, 25% in those exposed to 1–20 cigarettes, and 61% in those exposed to >20 cigarettes0.03
36 Six measures over 24 hoursAmplitude and mesor of PEF variability analysed by “rhythmometric” analysisChildren exposed and not exposed to cigarette smoke (validated by urinary cotinine)Amplitude was 0.14 l/s (60%) greater in exposed than in non-exposed children<0.02
Mesor (average level) was 0.29 l/s lower in exposed children<0.02
Age and sex were controlled for by design
37 Best of three readings taken morning and evening for one weekAverage over week of
Embedded Image
Current maternal smoking v not and no. of smokers in houseCurrent maternal smoking increased amplitude by 14% (95% CI 4 to 25) in non-asthmatics and by 55% (95% CI 6 to 126) in asthmatics after adjustment for current symptoms, atopy, air temperature and humidity0.006
38 Every four hours over a 24 hour period Embedded Image “Exposed” v “not exposed”
not defined
Amplitude in exposed group was 29.7% (95% CI 3.9 to 56.6) and in non-exposed was 19.4% (0.0 to 56.6)3-150 <0.05
Effect was very similar after adjustment for pets, house dust mite, age and bronchial reactivity
  • 3-150 Data given are for period off inhaled corticosteroid treatment. Results very similar while on treatment.