The Relationship Between Smoking, Obesity and Asthma, Essay Example

Results                                                                 

Pearson chi-square analyses were calculated to determine the likelihood the observed outcomes were the result of chance.  The number of those who developed asthma in the previous 12 months were found to differ based on whether they were smokers or non-smokers c² (1, N = 1295) = 7.59, p = .006.  The Odds Ratio showed that smokers developed asthma in the 12 months prior to the study 1.81 times more often than non-smokers. However, the majority of the smokers (87.3%) and non-smokers (92.9%) did not develop asthma.

The number of those who developed asthma in the 12 months prior to the study were found to differ based on whether or not subjects were in a normal weight range (calculated by the Body Mass Index), c² (1, N = 1252) = 22.02, p<.0001. Those within a normal weight range were significantly more likely to have developed asthma in the previous 12 months than those not within an average weight range.  The Odds Ratio showed that those who were in a normal weight range as indicated by the BMI developed asthma in the previous 12 months 2.36 times more often than those not in an optimal weight range.  However, once more the majority within a normal weight range (86.6%) and not within a normal weight range (94.3%), did not develop asthma in the previous 12 months.

Discussion

The development of asthma has been associated with smoking in some studies but not others. The consistent finding is that asthma severity appears to be associated with smoking (e.g. Thomson, Chaudhuri, & Livingston, 2004). However, while this study did not measure asthma severity, the sizable population studied here appears to provide some support to the studies showing the link between smoking and the presence or absence of asthma. A surprise finding was that being within an average weight range was associated with developing asthma in the previous 12 months.  It is unclear why this would be at this time as all the research to date shows that obesity is associated with asthma onset and severity (e.g.Huovinen, Kaprio, and Koskenvuo2003). It is possible that the failure to differentiate between those that were underweight and those that were overweight in the analyses, coding all these individual as a “no” on the variable of “within normal weight” caused these individuals to cancel each other out in comparison to the group which was coded as a “yes” on “within normal weight”.

Limitations

One limitation in the current study was that that the analyses did not differentiate between being under weight and being overweight, only whether someone was in a normal weight range on not within a normal weight range.  Thus, there might have been a positive effect of being slightly underweight which canceled out the effects of being overweight leaving the middle group or those in a normal weight range to appear to have greater odds of developing asthma in comparison. Another limitation was that it was not able to be determined when the onset of smoking and asthma occurred, whether they both had developed many years ago or whether they were more recent occurrences. Determining which of these two variable preceded the other was also not possible. While it may seem logical that those with asthma would not be likely to take up smoking it is not implausible that after developing asthma the worry over having a chronic illness lead some people to attempt to cope in an unhealthy manner. Finally, we did not examine the relationship between the demographics and the dependent and independent variables so could not determine if these variable might have contributed to the relationships observed or whether they confounded the findings.

Conclusions

This study was undertaken to provide additional information about factors that might contribute to asthma. Findings suggested a possible link between smoking and asthma and between body weight and asthma. Future studies should examine the relationship between these variables using a longitudinal design to tease out how weight and smoking contribute to the onset and severity of asthma individually as well as how they may contribute to asthma together. Groups should be differentiated based on whether subjects smoke or are over or under weight with a third group consisting of those who smoke and are overweight or are under weight. It would also provide a clearer picture if the variables were coded according to a continuous method instead of a dichotomous basis and if asthma severity were included.  By categorizing variables as “yes” of “no” or “present” or “absent” it is likely a great deal of informative information inherent in the data if examined more closely is being missed. Furthermore examining the contribution of demographic variables such as gender, age and race on asthma as well as on smoking behavior and obesity will yield important information for intervention.

References

Huovinen E., Kaprio J., and Koskenvuo M. (2003).Factors associated to lifestyle and risk of adult onset asthma.Respiratory Medicine, 97(3), 273-80.

Thomson, N. C. Chaudhuri, R., and Livingston, E. (2004). Asthma and cigarette smoking. European Respiratory Journal, 5, 822-833.