The article titled "Non-smoking wives of heavy smokers have a higher risk of lung cancer: a study from Japan" focuses on exactly what the title states: the effects on non-smoking wives of their smoking husbands. Importantly, the study indicates a relationship between second-hand smoke and lung cancer.
The study was designed as a 14-year analysis of the mortality rates for lung cancer in non-smoking wives with husbands who smoked various amounts per day. The aim of the study was to look at the relationship between passive smoking of the women and lung cancer. Not surprisingly, the results showed a clear relationship between the two. More specifically, the data shows that the effects of passive smoking is between one-half to one-third that of direct smoking in terms of mortality due to lung cancer. This is a relatively large number given that non-smokers exposed to smoking can be at a serious risk of the same disease as smokers.
More specifically, the study analyzed the age and occupation of the smoking husbands as well as how much he smoked. They found that women with husbands aged 40-59 at enrollment who worked in agriculture had the greatest risk of mortality due to lung cancer. Additionally, it is important to note that the study found no relationship between the husband's smoking habits and any other type of cancer in the non-smoking wive. There is a small relationship between the husband's smoking habits and the wife's risk of developing diseases such as emphysema and asthma, but this relationship was significantly small and therefore not focused on.
As detailed questions about lifestyle were asked of husbands and wives independently at the start of this study, this study design is particularly advantageous; the design allows for no subjective bias on either subject of the study. Therefore, all [or most] results are credible and conceivable.
Although I was not unaware that second-hand smoke is dangerous prior to reading this article, I was surprised by the immensity of the relationship between non-smokers exposed to second-hand smoke to lung cancer. This great relationship forces us to question whether or not it is useful to compare "smokers" to "non-smokers" when studying the risk of developing lung cancer from smoking, because the "non-smokers" could be exposed to large amounts of smoke. For example, a non-smoking wive who has a husband that smokes three packs of cigarettes a day could be exposed to even more smoke than a smoker who only smokes one or two cigarettes a day. To fix the problem, researchers should categorize the non-smokers based on how much second-hand smoke they are exposed to. This would allow for the results to be more accurate.
It is also important to note that these findings were not a result of chance. In other words, it is not an instance of chance that non-smoking wives with smoking husbands had a higher mortality rate due to lung cancer than non-smoking wives with non-smoking husbands. This is the case because as the results of the study show, there was a statistically significant relationship between the amount of cigarettes the husband smoked and the morality rates due to lung cancer of their non-smoking wives. This fact shows that there is a fine relationship between second-hand smoke and lung cancer in non-smokers.
I totally agree with you that the result of second hand smoking causes lung cancer is not a chance. It is definitely an awareness that the community or a population should take into consideration of what are the risks when they are exposed to these toxic materials. I think the same as you with this cohort study that was performed in Japan and how they divided their results and categorize them to show and relate what is happening to those that are affected. Also the relative risk and the population in this study did help analyze what was happening if this was a cause and effect situation/analysis.
ReplyDeleteI think you make an excellent point about the faulty distinction between smokers and non-smokers based on this study. Honestly, if a person is forced to deal with exposure to cigarette smoke on a regular basis from a pack a day smoker, they really are no better off then someone who smokes more moderately. There will now have to be better ways to express the dangers of not only smoking directly, but constantly finding yourself in an environment in which cigarettes are being smoked. There have been links between second hand smoking and respiratory issues documented and reported before, but this is the first time I've seen such a dramatic correlation between it and death expressed before.
ReplyDeleteI like your take on the article. Indeed, its satisfying to know that you did learn something new about passive smoking.
ReplyDeleteQn 3 is really looking for your understanding of the advantages of a cohort study. This is a cohort study where a group of people exposed to passive smoking are followed for a long time to assess a particular outcome (in this case, lung cancer).
Looking back at the lecture, some of the advantages of a cohort study are that it establishes that temporal relationship which allows for an investigator to be confident that the exposure came before the outcome.
This type of design is also good for studying multiple outcomes of a particular exposure. In this case, other types of cancers (like stomach, cervix) were also assessed. No association with passive smoking was found but its good to have been able to study this association.
Qn 4 is focusing on Hill's criteria for causation and if these were demonstrated in the paper. While you correctly note the dose-response relationship demonstrated in the article, the others to consider are the temporality in the study design, the strength of association, biological plausibility, etc