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- Olin, Anna-Carin, 1960, et al.
(författare)
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Increased fraction of exhaled nitric oxide predicts new-onset wheeze in a general population.
- 2010
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Ingår i: American journal of respiratory and critical care medicine. - 1535-4970. ; 181:4, s. 324-7
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Tidskriftsartikel (refereegranskat)abstract
- RATIONALE: Fraction of exhaled nitric oxide (Fe(NO)) is regarded as a marker of airway inflammation. It is unknown whether increased Fe(NO) in respiratorily healthy subjects increases the risk of developing wheeze. OBJECTIVES: To examine if increased levels of Fe(NO) predicts later onset of wheeze. METHODS: We followed up 2,200 men and women from a general population-based study. At baseline, the subjects were investigated with questionnaires, blood samples, pulmonary function tests, and Fe(NO). At follow-up 4 years later, all subjects were mailed a respiratory questionnaire. The association between incident wheeze and baseline levels of Fe(NO) over the 90th percentile were evaluated calculating hazard ratios using Cox regression models adjusted for smoking habits, age, height, sex, and atopy. MEASUREMENTS AND MAIN RESULTS: The follow-up questionnaire was completed by 1,896 subjects (86.2%). All subjects reporting wheeze, asthma, or asthma symptoms at baseline were excluded resulting in a study population of 1,506 subjects. Of these, 49 subjects reported new-onset wheeze. The median concentration of Fe(NO) at baseline was significantly higher among those with new-onset wheeze (18.8 ppb vs. 15.8 ppb, P = 0.03). In a Cox regression model including all subjects, Fe(NO) over the 90th percentile predicted onset of wheeze (hazard ratio 2.7; 95% confidence interval, 1.4-5.4). In stratified models, this was most apparent among never-smokers and in atopic subjects, for whom the odds ratios were higher. CONCLUSIONS: Our results indicate that increased Fe(NO) is associated with an increased risk of developing wheeze. The results also support the hypothesis that increased level of Fe(NO) among subjects without respiratory symptoms is a sign of subclinical airways inflammation.
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| 2. |
- Strandhagen, Elisabeth, 1960, et al.
(författare)
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Selection bias in a population study with registry linkage – potential effect on social gradient in cardiovascular risk
- 2010
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Ingår i: European Journal of Epidemiology. - 1573-7284. ; 25:3, s. 163-172
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Tidskriftsartikel (refereegranskat)abstract
- Non-participation in population studies is likely to be a source of bias in many types of epidemiologic studies, including those describing social disparities in health. The objective of this paper is to present a non-attendance analysis evaluating the possible impact of selection bias, when investigating the association between education level and cardiovascular risk factors. Data from the INTERGENE research programme including 3,610 randomly selected individuals aged 25-74 (1,908 women and 1,702 men), in West Sweden were used. Only 42% of the invited population participated. Non-attendance analyses were done by comparing data from official registries (Statistics Sweden) covering the entire invited study population. This analysis revealed that participants were more likely to be women, have university education, high income, be married and of Nordic origin compared to non-participants. Among participants, all health behaviours studied were significantly related to education. Physical activity, alcohol use and breakfast consumption were higher in the more educated group, while there were more smokers in the less educated group. Central obesity, obesity and hypertension were also significantly associated with lower education level. Weaker associations were observed for blood lipids, diabetes, high plasma glucose level and perceived stress. The socio-demographic differences between participants and non-participants indicated by the register analysis imply potential biases in epidemiological research. For instance, the positive association between education level and frequent alcohol consumption, may, in part be explained by participation bias. For other risk factors studied, an underestimation of the importance of low socioeconomic status may be more likely.
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