Background One of the sequelae of PTB is the development of CPA, with or without an aspergilloma. We estimated the global 5 year period prevalence of CPA.
Methods Estimation of the number of cases of PTB and deaths was made by the WHO. The frequency of pulmonary cavities after PTB treatment varied from 8% (Vietnam) to 35% (Taiwan), with rates in South Africa and US of 21–23% and Brazil of 30%; we used a rate of 22% except in Europe (12%). CPA (pulmonary cavity(s) + positive Aspergillus serology) annual incidence was estimated from PTB cases with cavities (22%) and without cavities (2%). Annual mortality following PTB varies from 5% (Denmark) to 15% (Uzbekistan) and is higher in HIV infected patients (26%) and those with MDR PTB (12%). We calculated the 5 year prevalence using annual attrition rates of 10–25%.
Results In 2007, WHO estimated 7.7M PTB cases globally, with 77.1% 1-year survival. We estimate that 372 385 patients worldwide developed CPA following PTB in 2007, distributed 11 420 (Europe), 12 610 (Americas), 98 551 (Africa), 20 615 (E. Mediterranean), 83 815 (W. Pacific) and 145 372 (SE Asia). In the UK, the annual new CPA caseload from PTB is estimated to be 118 cases with an estimated 5 year period prevalence of 433 cases. 5 year estimated CPA prevalence using median estimates above was:
|WHO region||Annual attrition (death or surgical resection) rate|
Sensitivity analyses using 10% or 30% rates of cavity formation after PTB and CPA rates in those without cavities (1% or 4%) alter the estimates from a low global 5 year prevalence rate of 546 844 to a high of 1 786 421 patients living with CPA, at a 15% attrition rate.
Conclusions CPA following PTB is a significant public health problem in Africa, W. Pacific and SE Asia. A lack of contemporary research limits the precision of estimates regionally and globally.