Distribution of peak expiratory flow variability by age, gender and smoking habits in a random population sample aged 20-70 yrs.

Peak expiratory flow (PEF) variability can be considered as an index of bronchial lability. Population studies on PEF variability are few. The purpose of the current paper is to describe the distribution of PEF variability in a random population sample of adults with a wide age range (20-70 yrs), and to assess relationships to age, gender and smoking habits. PEF data were collected in 511 participants of the Dutch part of the European Community Respiratory Health Survey. A training effect was found, absolute PEF values on the first measurement day being significantly lower. Females had greater PEF variability (adjusted for age, height and pack-years) and lower absolute PEFs than males. The mean within-day variation (amplitude % mean) was 3.66% (SD 2.03%), whereas the mean day-to-day variation was relatively small: 0.08% (SD 1.53%). Absolute PEFs were lower and amplitude % mean were significantly higher in older age groups. Smoking was significantly associated with lower mean PEFs and greater amplitude % mean. We observed lower mean values of the amplitude % mean than other investigators, possibly related to lower frequency of PEF recording (twice daily). We conclude that PEF and PEF variability have a normal or log-normal distribution. When studying PEF variability, age, gender and smoking habits should be taken into account.