Is Living in a Rural Area Good for Your Respiratory Health?

Results From a Cross-sectional Study in Scotland

Lisa Iversen, MSc; Philip C. Hannaford, MD; David B. Price, FRCGP; David J. Godden, MD

Disclosures

CHEST. 2005;128(4):2059-2067. 

In This Article

Discussion

Compared with respondents from urban practices, rural participants reported a significantly lower prevalence of asthma and eczema/dermatitis; a lower prevalence of respiratory symptoms (including wheeze); and, among those with COPD/emphysema or symptoms of chronic cough or phlegm, better scores in certain aspects of quality of life. This was a large study with a good geographic spread. In the United Kingdom, > 95% of the population are registered with a general practitioner.[29] Recruitment through general practices and their registers ensured as much as possible that the study population was representative of the general population. We looked at a number of respiratory conditions and symptoms affecting both young and older adults, allowing us to compare a number of aspects of health, including quality of life. The prevalence of respiratory disease reported by respondents from different locations could have been affected by differences in the participating general practices (eg, in the level of investigation undertaken or diagnostic terms used), as well as by differences in the recall of diagnoses. It is noteworthy, however, that differences also existed between participants from different locations in the reporting of symptoms, which are unlikely to have been affected by such problems. There were no differences between rural and urban respondents in patterns of asthma-related treatment. Further research is needed into whether there are important geographic variations in the presentation of respiratory symptoms to general practices, and in their subsequent management.

Response bias may have occurred if recipients of the questionnaire chose to participate in the study depending on the presence of chronic respiratory disease. Selection bias may have arisen from the 60% response rate and from the different response rates from rural and urban participants. Respondents were more likely to be women and were older than nonrespondents. Although respondents from rural practices were more likely to be retired than respondents from urban practices, they were not older. We do not know why the respondents had retired, and so it is difficult to know how these differences may have affected our findings. If rural respondents had retired because of poor respiratory health, it is unlikely to explain the rural/urban differences observed. Alternatively, if respondents from rural practices had retired early due to ill health from conditions other than respiratory disease, and these conditions were mutually exclusive from respiratory disease, this may account for some of the Results. However, we found no significant excess of other diseases among rural respondents.

Other research about respiratory symptoms and illness found that nonrespondents were more likely to be current smokers, manual workers, and have a higher prevalence of asthma and a number of respiratory symptoms than respondents to a postal questionnaire.[30] If similar problems affected our Results, we will have underestimated the prevalence of respiratory problems. The small number of respondents reporting some respiratory conditions limited the statistical power of our study to examine further rural/urban relationships for these problems. We may, therefore, have missed differences that exist between areas. In addition, we were restricted in our ability to explore in detail geographic differences in quality of life scores of respondents reporting COPD or emphysema.

Our Results relied on self-reported information and could have been affected by information bias. An Australian study[31] among middle-aged and older adults found little difference between the self-reported prevalence of ever asthma, chronic bronchitis and emphysema, and the prevalence of these conditions confirmed by a doctor. A cross-sectional study investigating the relationship between pulmonary test variables and self-reported asthma and wheeze concluded that questions about the self-report of asthma and wheezing had high criterion validity when compared with concurrently measured pulmonary function variables.[32]

The Detection, Intervention, and Monitoring of COPD and Asthma study[33] of 1,155 subjects recruited from 10 general practices in the Netherlands found that 50% of the general population from 25 to 70 years old had respiratory symptoms or objective indicators of obstructive airways disease. A postal survey (based on the MRC questionnaire) of obstructive lung disease among 6, 610 adults aged 35 to 36, 50 to 51, and 65 to 66 years in northern Sweden found no difference in the occurrence of self-reported asthma or respiratory symptoms between rural and urban areas.[34] Our Results broadly concur with the findings of the European Community Respiratory Health Survey, in which the prevalence rates of respiratory symptoms were found to be particularly high among the UK centers.[5] We found a higher prevalence of asthma among adults than previously reported in large-scale Scottish surveys but a similar prevalence of wheeze.[35] Differences may partly be due to differences in study methodology. We adjusted our Results for group differences in socioeconomic circumstances as well as other possible confounders including age, gender, and smoking. It is possible, however, that residual confounding may account, at least in part, for the remaining differences.

The cross-sectional nature of our study prevents us from distinguishing between cause and effect in any relationships found. Nevertheless, it is important to consider why there might be rural/urban differences in the prevalence of self-reported asthma and asthma- related symptoms (if real). There may be differences between rural and urban areas that were not measured, such as atmospheric pollution, body mass index (BMI), diet, exposure to farming and occupational exposures, which may account for the observations. For instance we did not collect information to allow us to calculate BMI, which has been shown to be important for chronic respiratory disease.[36,37] Rural/urban differences in the prevalence of asthma could have occurred if urban respondents with a high BMI were more likely to be diagnosed as having asthma than rural respondents who had a high BMI. This seems unlikely, but further research is required to examine this.

In our study, rurality was defined on the basis of current residency. We do not know if the participants were of rural origin. In France, the prevalence of asthma and adult allergy was found to be significantly lower in those who had ever lived in the country, particularly in subjects who began living in the country before 17 years of age.[38] Evidence from a study of Swedish conscripts suggests that the protective effect of farming environments during childhood on adult asthma is a recent phenomenon observed only among conscripts born after 1970.[39] In Austria, children living on a farm were found to have less asthma, hay fever, and allergic sensitization than children from a nonfarming environment.[40] Children who did not live on a farm but who had regular contact with farm animals had a lower prevalence of allergic sensitization, suggesting that contact with livestock might have a protective role against allergy, perhaps through greater exposure to infections. There is some evidence that if the immune system is exposed to high levels of allergen, as might be the case in rural settings, a form of immune tolerance may occur, perhaps resulting in less allergic disease.[41]

Respondents with chronic respiratory disease reported impaired quality of life on both generic and disease-specific measures. The apparently better quality of life of respondents with COPD or emphysema living in rural areas might be explained by confounding by socioeconomic or other factors such as perhaps differences in severity. Unfortunately we had too little data to enable us to adjust our Results for these variables. This merits investigation in a larger study.

Our Results indicate that living in a rural area is associated with a lower prevalence of asthma but not other chronic respiratory disease, and a lower prevalence of some respiratory symptoms. Although the prevalence of COPD or emphysema may not differ between rural and urban areas, rural residency may be associated with better health status among subjects with these conditions.

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