Academic journal article Bulletin of the World Health Organization

A Tuberculosis Nationwide Prevalence Survey in Gambia, 2012/ Enquete Sur la Prevalence De la Tuberculose a L'echelle Nationale En Gambie En 2012/ Una Encuesta Nacional De Prevalencia De la Tuberculosis En Gambia, 2012

Academic journal article Bulletin of the World Health Organization

A Tuberculosis Nationwide Prevalence Survey in Gambia, 2012/ Enquete Sur la Prevalence De la Tuberculose a L'echelle Nationale En Gambie En 2012/ Una Encuesta Nacional De Prevalencia De la Tuberculosis En Gambia, 2012

Article excerpt

Introduction

Tuberculosis killed 1.5 million people in 2014 and is the leading cause of death from an infectious disease worldwide. (1) Sub-Saharan Africa, with 28% (9.6 million) of all notified tuberculosis cases in 2014, endures a disproportionate burden of the disease relative to its population. In Gambia, the estimated incidence and prevalence of tuberculosis rose from 258 and 350 per 100000 population respectively in 1990 to 284 and 490 per 100000 in 2011. (2) In addition, the tuberculosis case detection rate--that is, the ratio of the number of notified tuberculosis cases to the number of incident tuberculosis cases in a given year--remained low at 48% (95% confidence interval, CI: 40-58). (2) It is not clear if poor case detection is due to inequitable access to care or inadequate diagnosis of tuberculosis in urban or remote parts of the country.

Given the need for improved, evidence-based interventions in tuberculosis control in Gambia, it is important to establish reliable baseline estimates of tuberculosis prevalence against which future control interventions can be assessed. This study therefore aimed to estimate the population prevalence of active pulmonary tuberculosis disease in Gambia, in 2012 and to compare the case detection rate with global tuberculosis control targets.

Methods

Study design

We carried out a nationwide, multistage cluster survey in 2011-2013. A sample size of 55 281 participants [greater than or equal to] 15 years old from 80 clusters was calculated assuming a prevalence of 292 sputum smear-positive cases per 100000 population, (3) 85% participation target, design effect of 1.51 and application of a finite population correction. (4) A sample size with 80 clusters was expected to give around 20% precision and higher than 25% precision under the most plausible scenarios, and with an intracluster coefficient ofvariation of 0.5 the calculated design effect was 1.51.

Sampling to select survey areas was multistage and without any stratification. First, we allocated 80 survey enumeration areas by regions of the country in proportion to population size based on the national 2003 census (Central Statistics Department, Government of Gambia). Following this allocation, the West Coast region with about 28.7% (389274) of the population was to contribute 23 enumeration areas and the least populated Lower River region contributed four enumeration areas for 5.3% (72184) of the population. This procedure was similar in outcome to the recommended sampling in proportion to population size. (4) Then we randomly selected the survey enumeration areas (e.g. 23 for the West Coast region) up to a total of 80 for the entire country. Each selected survey enumeration area was paired with between one and two adjacent enumeration areas in whole or part until an adult population of 500-700 was attained.

People eligible for participation were all those aged [greater than or equal to] 15 years; permanent residents who spent at least one night in the household in the preceding 4 weeks; and visitors who had arrived in the household 4 weeks or more before.

Study procedures

Three teams--each consisting of a research clinician who led a team of 7 trained fieldworkers and a radiographer--performed the fieldwork from December 2011 to January 2013. Data collection in each cluster was done over a seven-day period. The field workers, in collaboration with community-selected liaisons, enumerated the population in each cluster 4-6 weeks before actual data collection. The field workers visited the enumerated households to obtain data on household composition and residency, and at the same time discussed the purpose of the survey. For families that were not at home, the team were informed at which time they could return to meet the household members. Community entry meetings with the local chief and other community leaders were also held to provide further information. …

Search by... Author
Show... All Results Primary Sources Peer-reviewed

Oops!

An unknown error has occurred. Please click the button below to reload the page. If the problem persists, please try again in a little while.