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Falaschetti E, Laiho J, Primatesta P, Purdon S: Prediction equations for normal and low lung function from the Health Survey for England. Eur Respir J 2004; 23: 456-463.The design of the HSE, an annual nationwide household survey of the English population, has been described in detail elsewhere [6]. Briefly, members of a stratified random sample, sociodemographically representative of the English population, were invited to participate in 1995 and 1996. The mean response rate was >75% in both years, but slightly lower than average amongst males and in inner cities. Data on each respondent were collected during two visits, with identical methods used in 1995 and 1996: an interviewer's visit, during which a questionnaire was administered and height and weight measured, followed by a nurse's visit, during which lung function was measured (amongst other investigations). Smoking habits and any respiratory symptoms were recorded in the questionnaire.Lung function was measured using the Vitalograph Escort Spirometer (Vitalograph, Buckingham, UK), a portable device. A standardised protocol was used and all nurses who took the measurements received identical training and were subjected to repeated briefings during the study period. Before starting any measurements within a household, the spirometer was always calibrated using a 1-L calibration syringe. The nurse then demonstrated the test procedure to the respondents within the household. While in a standing position (unless chairbound), respondents were required to perform a forced inspiration followed by an expiration with maximal effort, without excitation or bending forward. A test was considered technically acceptable if none of the following occurred: an unsatisfactory start of expiration, breath-holding, an obstructed mouthpiece, or the lips not being properly sealed around the mouthpiece. Five consecutive readings were taken, and forced expiratory volume in one second (FEV1) and forced vital capacity (FVC) recorded using the best value from any of the acceptable measurements. Those subjects who gave only unsatisfactory tests were excluded from the analysis. The American Thoracic Society (ATS) acceptability and reproducibility criteria [7] were not applied in this population sample. However, for the purpose of the present study, subjects who did not meet the reproducibility criteria were excluded as individuals with asthma often have problems with reproducibility criteria [8]. The analysis was restricted to White respondents aged >16 yrs, since lung function values for non-Whites and younger children are known to differ systematically from those in the White older group. Only "healthy" subjects were used in the derivation of prediction equations. The "healthy" group was defined, according to ATS recommendations, as nonsmokers (both exsmokers and current smokers excluded) with no reported diagnosis of asthma or respiratory symptoms (wheeze in the last 12 months; cough/phlegm for >3 months/yr; shortness of breath at night, when walking with peers on level ground, when hurrying on level ground or when walking up a slight hill; or on asthma medication in the last 12 months) (table 1). References6. Prescott-Clarke P, Primatesta P, eds. The Health Survey for England 1996. Vol. 2. London, The Stationery Office, 1998.7. American Thoracic Society. Standardization of Spirometry, 1994 Update. Am J Respir Crit Care Med 1995; 152: 1107–1136. 8. Pennock BE, Rogers RM, McCaffree DR. Changes in measured spirometric indices: what is significant? Chest 1981; 80: 97–99. |
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