Case–control study of indoor cooking smoke exposure and cataract in Nepal and India

Case–control study of indoor cooking smoke exposure and cataract in Nepal and India (pdf)
Amod K Pokhrel,1 Kirk R Smith,1 Asheena Khalakdina,1,2 Amar Deuja3 and Michael N Bates1*

International Journal of Epidemiology 2005;34:702–708 28 February 2005

Background:
The prevalence of cataract is higher in developing countries, and in both
developed and developing countries more females than males are blind from
cataracts. Three epidemiological studies have associated indoor cooking with
solid fuels (e.g. wood or dung) and cataract or blindness. However, associations
in these studies may have been caused by unmeasured confounding.

Methods:
A hospital-based case–control study was conducted on the Nepal–India border. Cases (n = 206) were women patients, aged 35–75 years with confirmed cataracts.
Controls (n = 203), frequency matched by age, were patients attending the refractive
error clinic at the same hospital. A standardized questionnaire was administered to
all participants. Logistic regression analysis involved adjustment for age, literacy,
residential area, ventilation, type of lighting, incense use, and working outside.

Results:
Compared with using a clean-burning-fuel stove (biogas, LPG, or kerosene), the adjusted odds ratio (OR) for using a flued solid-fuel stove was 1.23 [95%
confidence interval (CI) 0.44–3.42], whereas use of an unflued solid-fuel stove
had an OR of 1.90 (95% CI 1.00–3.61). Lack of kitchen ventilation was an
independent risk factor for cataract (OR 1.96; 95% CI 1.25–3.07).

Conclusion:
This study provides confirmatory evidence that use of solid fuel in unflued indoor stoves is associated with increased risk of cataract in women who do the cooking.

The association is not likely to be due to bias, including confounding, and
strengthens the findings of three previous studies. Replacing unflued stoves with
flued stoves would greatly reduce this risk, although cooking with cleaner burning
fuels would be the best option.
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1 School of Public Health, 140 Warren Hall, University of California, Berkeley,
CA 94720-7360, USA.
2 Present address: WHO Regional Office for South-East Asia, World Health
House, Indraprastha Estate, Mahatma Gandhi Marg, New Delhi 110 002,
India.
3 Shree Rana Ambika Shah Eye Hospital, Lumbini Zone, Nepal.
* Corresponding author. 140 Warren Hall, University of California, Berkeley,
CA 94720-7360, USA. E-mail: m_bates@berkeley.edu

Cited in PCIA Bulletin Issue 7, June 2006