Table 3
Summary of results of studies of circadian variation in measurements of peak expiratory flow (PEF)
| Reference no. | Number of PEF measurements | Outcome measure used | Exposure comparison | Results | p value | |||||
|---|---|---|---|---|---|---|---|---|---|---|
| 35 | Not given | Not given | Cigarettes 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 cigarettes | 0.03 | |||||
| 36 | Six measures over 24 hours | Amplitude and mesor of PEF variability analysed by “rhythmometric” analysis | Children 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 week | Average over week of
| Current maternal smoking v not and no. of smokers in house | Current 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 humidity | 0.006 | |||||
| 0.026 | ||||||||||
| 38 | Every four hours over a 24 hour period |
| “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.