Epi in the News

Hi Sujit,

The following are my answers:

1. These are prevalence figures.
The numerator is people living with diabetes in India, i.e. 101 million, and the denominator is total population in India.

2. I believe that it is better to use the term “person with diabetes” rather than stamping/stigmatizing a person as “diabetic”.

3. The perfect but expensive way to measure participants’ exposure to air pollution would be using personal exposure monitor or measuring biological markers, if any.

Using satellite data and air pollution exposure models is a common way to measure air pollution, but there is risk of biased exposure estimates due to measurement error. Personal exposure is affected by time and activity or mobility patterns of the individuals which will not be reflected in the exposure measurement by using satellite data and exposure models.

4. The relative risk figure which corresponds to 22% is 1.22.
The name of this relative risk is risk ratio.

5. I think these findings are not generalisable beyond India. Because the air quality, its standards and the population characteristics are different in other countries. The results will also be affected by the the way the exposure and outcome are measured.

6. a. This is a prospective cohort study.

b. The exclusion criteria is those who are already suffering from diabetes or pre-diabetes.

c. The outcome was diabetes incidence.

7. The mediation/causal pathway for PM2.5 to cause diabetes is hampering insulin production and its effects in the body, and thereby acting as an endocrine disruptor.

8. It is not possible to conduct a randomised controlled trial in this case due to ethical reasons. The association can be proved by a well designed observational (case-control/cohort) study.

Thanks!
Madhutandra

Hi! Thanks for those questions - I will try to respond. However, I do need help with the Q. 4. I am not sure if I understand the question.

1) Are these incidence figures or prevalence figures? What is in the numerator and denominator for the 11.4% calculation?
- Prevalence rate; and the denominator is the general population in India - # of the whole population. Numerator is 110 mil people with diabetes.

2. Not specifically related to epidemiology, but I don't care for the word "diabetics" in this sentence. Why not?
- The language is stigmatizing - people with diabetes are described as medical cases rather than as patients.

3. If you had unlimited resources, what would be the perfect way to measure participants' exposure to air pollution? Comment on the risk of bias for the way the researchers actually did the exposure measurement. Is this good enough?
- It is assumed that if individual exposure to the air pollution is directly linked to the air population in the locality of the residence. There may be other factors that determine individual exposure to the air pollution - nature of work, distance to work, use of public transportation, ventilation conditions at home/work environment.

4. What is the relative risk figure which corresponds to 22%? What is the name of this relative risk?
- Could you help me with this? I am not sure if I understand the question! Sorry!

5. Do you think these findings are generalisable beyond India?
- The linkage between increasing air pollution and increasing rate of people with diabetes and hypertension can be generalized to a certain extent - as the physical effect of PM2.5 containing sulfate and nitrates, and heavy metals and black carbon can be generalized to other populations living in similar conditions. However, while the similar physical effect maybe observed in other countries, depending on the diet, access to early diagnosis and health care, and other factors could mitigate the risk of developing diabetics or hypertension.

Thanks!

Hyeyoung

Hi!
I see the link for the Lancet study and The Guardian article, but somehow I don't see the one for the BMJ study you are referring to. Could you tell me where it is? Thank you

Ante

Hello I have some responses:
1. Are these incidence figures or prevalence figures? What is in the numerator and denominator for the 11.4% calculation?
A: This is prevalence- numerator being the people of India living with Diabetes/Denominator- Population of India at risk.
2.Not specifically related to epidemiology, but I don't care for the word "diabetics" in this sentence. Why not?
A: We can remove any taboo associated with diabetes by avoiding terminology

3. If you had unlimited resources, what would be the perfect way to measure participants' exposure to air pollution? Comment on the risk of bias for the way the researchers actually did the exposure measurement. Is this good enough?
A. Aside the excellent model that was made, I would have wanted to take a note of the individual indoor air pollution as they already stated in their limitation...'Further, lack of quantified indoor
PM2.5, which also exists in urban environments, is a limitation in our study'
4.What is the relative risk figure which corresponds to 22%? What is the name of this relative risk?
A The relative Risk figure corresponding to 22% is 1.22-Known as Hazard Ratio in the paper
5. Do you think these findings are generalisable beyond India?
A. The study, as they put forth in their limitations- '...results are based on a cohort located in two urban environments in India, which limits the generalizability of the results across the country.'