Jørgen Nyboe

Spirometric findings and mortality in never-smokers

The relation of ventilatory function to overall mortality has been studied in 662 male and 2048 female never-smokers who during the period 1976-1978 participated in the Copenhagen City Heart Study, a prospective community study of more than 14,000 men and women randomly selected from the general population of the City of Copenhagen. Until the end of 1986, 195 subjects who said they were never-smokers died. Mortality was analyzed using the proportional hazards model of Cox. In addition to measures of ventilatory function, the mortality analysis included age, sex, body-mass index, alcohol consumption, school education, diabetes mellitus, heart disease and bronchial asthma as confounding factors. Forced expiratory volume in 1 second (FEV1) as a percentage of that predicted, forced vital capacity (FVC) as a percentage of that predicted and the ratio of FEV1 to FVC were significant risk factors for mortality among both sexes. The relative risk of death associated with a 50% decrease in FEV1 and FVC as a percentage of a predicted value was 1.65 and 1.81, respectively. This study confirms that lowered ventilatory function is a strong risk factor for mortality among never-smokers of both sexes.

Chronic obstructive lung disease in Copenhagen: cross-sectional epidemiological aspects

Abstract Lange P, Groth, S, Nyboe J, Appleyard M, Mortensen J, Jensen G, Schnohr P (Copenhagen City Heart Study, Medical Department B and Department of Clinical Physiology and Nuclear Medicine KF, Rigshospitalet, and Medical Department P, Bispebjerg Hospital, Copenhagen, Denmark). Chronic obstructive lung disease in Copenhagen: cross‐sectional epidemiological aspects.

Gray hair, baldness, and wrinkles in relation to myocardial infarction : the Copenhagen City Heart Study

To investigate a possible relation between aging signs such as graying of the hair, baldness, and facial wrinkling and myocardial infarction (MI), we analyzed data from The Copenhagen City Heart Study. During the 12-year follow-up, 750 cases of first-time MI were observed. After statistical adjustment for possible confounders, we found a correlation between graying of the hair, facial wrinkling, and frontoparietal baldness and crown-top baldness and MI in men. For example, the relative risk was 1.4 (95% CI, 0.9 to 2.0) for men with moderately gray hair compared with men with no gray hair and 1.9 (1.2 to 2.8) for men with completely gray hair (p < 0.001). With regard to gray hair, a similar although weaker and not statistically significant trend was seen in women. We conclude that, in addition to established coronary risk factors, aging signs like graying of the hair, male baldness, and facial wrinkling indicate an additional risk of MI.

Lung mucociliary clearance

The aim of this study was to establish reference values for mucociliary clearance and mucociliary clearance reserve capacity as determined by β 2-adrenergic agonist-induced increase in mucociliary clearance. We studied 62 healthy females (n=33) and males (n=29). Their ages ranged evenly between 18 and 84 years. Fifty-three of the subjects were life-long non-smokers, while nine were ex-smokers. Multiple linear regression analyses showed that mucociliary clearance was significantly faster when the radioaerosol was deposited in the central airways than when it was deposited in the peripheral airways, and faster in life-long non-smokers than in ex-smokers. There was no influence of age, and no convincing association with sex. The variation was less within than between subjects. Mean mucociliary clearance reserve capacity was 21.3% (SD: 10.0%, P<0.0001). The β 2 agonist-induced increase in lung mucociliary clearance was significantly larger (P<0.05) than the stimulation which has previously been reported in patients with asthma, bronchiectasis or cystic fibrosis. The signal-to-noise ratio of the mucociliary clearance reserve capacity in relation to measurement of baseline mucociliary clearance indicates that measurement of mucociliary clearance reserve capacity may be a more efficient means of distinguishing between “normal” and “abnormal” mucociliary clearance than single measurement of baseline mucociliary clearance.

Smoking and the risk of first acute myocardial infarction

When analyzing risk factors for first acute myocardial infarction in the Copenhagen City Heart Study, a large prospective population study of 20,000 men and women, smoking was found to influence risk significantly in a dose-dependent manner, the risk increasing 2% to 3% for each gram of tobacco smoked daily. Risk was particularly associated with inhalation, the risk for inhalers being almost twice that of noninhalers. No difference in risk could be demonstrated between various types of tobacco (pipe, cigar/cheroots, or plain and filtered cigarettes). The risk seemed associated with current smoking only, inasmuch as the duration of the smoking habit was not important. Ex-smokers had the same risk as those who had never smoked regardless of duration of smoking and time elapsed since quitting. Relative excess risk was significantly higher in female smokers than in male smokers, and daily alcohol intake appeared to have some protective effect on the risk of first acute myocardial infarction among heavy smokers.

Phlegm production in plain cigarette smokers who changed to filter cigarettes or quitted smoking

Abstract. Data from a prospective epidemiological study that included 2025 plain cigarette smokers were analysed to investigate the effect on phlegm production of changing to filter cigarettes or quitting smoking. During a 5‐year follow‐up, 189 subjects quitted smoking, 312 changed to filter cigarettes, while 1524 continued to smoke plain cigarettes. Multiple logistic regression was used to adjust for age, duration of smoking, number of cigarettes smoked, socio‐economic status and alcohol consumption. Smokers with morning phlegm at enrolment, who changed to filter cigarettes during the follow‐up, had a probability ratio of 1.9 of phlegm production ceasing, compared with smokers who continued to smoke plain cigarettes (P < 0.05). However, the probability ratio of developing morning phlegm among smokers who changed to filter cigarettes compared to those who continued to smoke plain cigarettes was 1.6 (P < 0.05). The overall prevalence of morning phlegm at the end of the follow‐up was the same in smokers who changed to filter cigarettes as in persistent plain cigarette smokers. The trends for chronic phlegm were similar, although they did not reach statistical significance. The smokers who stopped smoking had a probability ratio of 0.4 of developing morning phlegm (P < 0.01) and a ratio of 7.7 for ceasing to produce it (P < 0.001) compared to the smokers who continued to smoke plain cigarettes. Our results suggest that changing from plain to filter cigarettes is associated with a higher frequency of cessation of phlegm production, but offers no protection against the development of phlegm.