Seasonal variations in tuberculosis diagnosis among HIV-positive individuals in Southern Africa : analysis of cohort studies at antiretroviral treatment programmes
Date
2018-01
Journal Title
Journal ISSN
Volume Title
Publisher
BMJ Publishing Group
Abstract
Objectives Seasonal variations in tuberculosis diagnoses
have been attributed to seasonal climatic changes
and indoor crowding during colder winter months. We
investigated trends in pulmonary tuberculosis (PTB)
diagnosis at antiretroviral therapy (ART) programmes in
Southern Africa.
Setting Five ART programmes participating in the
International Epidemiology Database to Evaluate AIDS in
South Africa, Zambia and Zimbabwe.
Participants We analysed data of 331 634 HIV-positive
adults (>15 years), who initiated ART between January
2004 and December 2014.
Primary outcome measure We calculated aggregated
averages in monthly counts of PTB diagnoses and ART
initiations. To account for time trends, we compared
deviations of monthly event counts to yearly averages, and
calculated correlation coefficients. We used multivariable
regressions to assess associations between deviations
of monthly ART initiation and PTB diagnosis counts from
yearly averages, adjusted for monthly air temperatures
and geographical latitude. As controls, we used Kaposi
sarcoma and extrapulmonary tuberculosis (EPTB)
diagnoses.
Results All programmes showed monthly variations
in PTB diagnoses that paralleled fluctuations in ART
initiations, with recurrent patterns across 2004–2014. The
strongest drops in PTB diagnoses occurred in December,
followed by April–May in Zimbabwe and South Africa. This
corresponded to holiday seasons, when clinical activities
are reduced. We observed little monthly variation in ART
initiations and PTB diagnoses in Zambia. Correlation
coefficients supported parallel trends in ART initiations and
PTB diagnoses (correlation coefficient: 0.28, 95% CI 0.21
to 0.35, P<0.001). Monthly temperatures and latitude did
not substantially change regression coefficients between
ART initiations and PTB diagnoses. Trends in Kaposi
sarcoma and EPTB diagnoses similarly followed changes
in ART initiations throughout the year.
Conclusions Monthly variations in PTB diagnosis at ART
programmes in Southern Africa likely occurred regardless of seasonal variations in temperatures or latitude and
reflected fluctuations in clinical activities and changes in
health-seeking behaviour throughout the year, rather than
climatic factors.
Description
CITATION: Ballif, M. et al. 2018. Seasonal variations in tuberculosis diagnosis among HIV-positive individuals in Southern Africa: analysis of cohort studies at antiretroviral treatment programmes. BMJ Open 8(1):e017405, doi:10.1136/bmjopen-2017-017405.
The original publication is available at https://bmjopen.bmj.com/
The original publication is available at https://bmjopen.bmj.com/
Keywords
TB, Tuberculosis, Pulmonary tuberculosis -- PTB, Antiretroviral therapy programmes, Antiretroviral therapy-- ART, AIDS, HIV, South Africa, Zambia, Zimbabwe
Citation
Ballif, M. et al. 2018. Seasonal variations in tuberculosis diagnosis among HIV-positive individuals in Southern Africa: analysis of cohort studies at antiretroviral treatment programmes. BMJ Open 8(1):e017405, doi:10.1136/bmjopen-2017-017405.