Recent diarrhoeal illness and risk of lower respiratory infections

Int J Epidemiol. 2009 Jun;38(3):766-72.

(Comment in: Int J Epidemiol. 2009 Jun;38(3):772-4.)

Recent diarrhoeal illness and risk of lower respiratory infections in children under the age of 5 years.

Schmidt WP, Cairncross S, Barreto ML, Clasen T, Genser B.

Department for Infectious and Tropical Diseases, London School of Hygiene and
Tropical Medicine, London, UK. Wolf-Peter.Schmidt@lshtm.ac.uk

BACKGROUND: Children in low-income settings suffering from frequent diarrhoea episodes are also at a high risk of acute lower respiratory infections (ALRI). We explored whether this is due to common risk factors for both conditions or whether diarrhoea can increase the risk of ALRI directly.

METHODS: We used a dynamic time-to-event analysis of data from two large child studies in low-income settings in Ghana and Brazil, with the cumulative diarrhoea prevalence over 2 weeks as the exposure and severe ALRI as outcome. The analysis was adjusted for baseline risk of ALRI and diarrhoea, seasonality and age.

RESULTS: The child population from Ghana had a much higher risk of diarrhoea, malnutrition and death than the children in Brazil. In the data from Ghana, every additional day of diarrhoea within 2 weeks increased the risk of ALRI by a factor of 1.08 (95% CI 1.00-1.15). In addition, we found a roughly linear relationship between the number of diarrhoea days over the last 28 days and the risk of ALRI. In the Ghana data, 26% of ALRI episodes may be due to recent exposure to diarrhoea. The Brazilian data gave no evidence for an association between diarrhoea and ALRI.

CONCLUSION: Diarrhoea may contribute substantially to the burden of ALRI in malnourished child populations.

Fuel use and design of improved cookstoves in Guatemala

From Kirk Smith’s website:

Fuel use and design analysis of improved woodburning cookstoves in the Guatemalan Highlands. IN: Biomass and Bioenergy 33(2009) 306-315. (pdf, full-text)

Jessica Granderson, Jaspal S. Sandhu, Domitila Vasquez, Expedita Ramirez, Kirk R. Smith

This study examined the fuel use and design of an improved woodburning cookstove ( plancha), in comparison to traditional cooking over an open woodfire. These cookstoves had been randomly introduced into population households in the Guatemalan Highlands that had previously used open woodfires. This research consisted of: (1) a 12-household Kitchen Performance Test (KPT) over a 4-day period and (2) single-day participant observation in five households. The KPT monitored fuel consumption and the number, age, and gender of people who were cooked for, while the participant observation was used to form a complete understanding of fuel use patterns and to examine the influence of stove condition and cooking behavior. In spite of fairly low variability in the fuel use data (coefficients of variation of about 0.34) the KPT did not show statistically significant differences in fuel use between the two cooking methods. It is possible that increased study power through a larger sample size may have resulted in a statistically significant difference in favor of the plancha, but it is doubtful that the size of the effect would be of any practical significance. Thus, although other studies have shown that the plancha is extremely effective in reducing indoor air pollution in the study area, the KPT did not indicate that it offered any benefits with respect to fuel use. Practical and experimental recommendations for future cookstove efficiency studies are presented, with directions for continued work in this area.

Indoor air pollution – RESPIRE/Guatemala study 2009 (full-text)

From Kirk Smith’s website:

Effect of reducing indoor air pollution on women’s respiratory symptoms and lung function. RESPIRE Guatemala randomized trial.IN: Am J Epidemiology, 170(2): 211-220, 2009. (pdf, full-text)

Tone Smith-Sivertsen, Esperanza Dı´az, Dan Pope, Rolv T. Lie, Anaite Dı´az, John McCracken, Per Bakke, Byron Arana, Kirk R. Smith, and Nigel Bruce

Exposure to household wood smoke from cooking is a risk factor for chronic obstructive lung disease among women in developing countries. The Randomized Exposure Study of Pollution Indoors and Respiratory Effects (RESPIRE) is a randomized intervention trial evaluating the respiratory health effects of reducing indoor air pollution from open cooking fires. A total of 504 rural Mayan women in highland Guatemala aged 15–50 years, all using traditional indoor open fires, were randomized to either receive a chimney woodstove (plancha) or continue using the open fire. Assessments of chronic respiratory symptoms and lung function and individual measurements of carbon monoxide exposure were performed at baseline and every 6 months up to 18 months. Use of a plancha significantly reduced carbon monoxide exposure by 61.6%. For all respiratory symptoms, reductions in risk were observed in the plancha group during follow-up; the reduction was statistically significant for wheeze (relative risk ¼ 0.42, 95% confidence interval: 0.25, 0.70). The number of respiratory symptoms reported by the women at each follow-up point was also significantly reduced by the plancha (odds ratio ¼ 0.7, 95% confidence interval: 0.50, 0.97). However, no significant effects on lung function were found after 12–18 months. Reducing indoor air pollution from household biomass burning may relieve symptoms consistent with chronic respiratory tract irritation.