Peak expiratory flow from maximum expiratory flow volume curves in a community population: Cross-sectional and longitudinal analyses

The data from a longitudinal population study in Tucson, Arizona, were used to describe the development and decline with age of the peak expiratory flows (PEF) from maximum expiratory flow-volume (MEFV) curves derived using a computer-linked pneumotachometer. Subjects had performed at least one technically acceptable MEFV test in 9 of the first 11 surveys (1972-1989). There were 2,724 subjects with adequate MEFV curves, and thus PEF, in the first survey, but only 1315 in the 11th survey. The subjects were stratified based on responses to questionnaires into nonsmoking healthy subjects and others. The PEF were analysed cross-sectionally and longitudinally using data from the 6th-11th surveys (1979-1989). For longitudinal analysis, the reference population had 397 males with 1,153 observations, and 534 females with 1,700 observations. The resulting equations were compared, evaluating differences between the longitudinal and cross-sectional equations, and between reference and nonreference longitudinal populations. The results show that there were effort-dependent effects in absolute values of PEF, even after editing. Nevertheless, as with most MEFV measures in reference populations, PEF had an early increase in the rate of development, followed by a plateau phase, followed by a constant rate of decline. The ages at which changes in growth rates of PEF occurred differed by gender. The longitudinal data in adults showed a less steep decline with age compared to the cross-sectional data, as found previously for the other MEFV variables. Males in the nonreference group did not reach the same maximum level and had a steeper decline throughout adult life than did males in the reference group; females were similar. Asthmatics of both genders had slightly greater declines compared to the other nonreference subjects.