Academic journal article Bulletin of the World Health Organization

Global Burden of Chronic Pulmonary Aspergillosis as a Sequel to Pulmonary tuberculosis/Charge Globale De L'aspergillose Pulmonaire Chronique Comme Sequelle De la Tuberculose pulmonaire/Carga Global De la Aspergilosis Pulmonar Cronica Como Una Secuela De la Tuberculosis Pulmonar

Academic journal article Bulletin of the World Health Organization

Global Burden of Chronic Pulmonary Aspergillosis as a Sequel to Pulmonary tuberculosis/Charge Globale De L'aspergillose Pulmonaire Chronique Comme Sequelle De la Tuberculose pulmonaire/Carga Global De la Aspergilosis Pulmonar Cronica Como Una Secuela De la Tuberculosis Pulmonar

Article excerpt

Introduction

With more than 36 million people cured of tuberculosis between 1995 and 2008 (1) and 9 million new cases diagnosed worldwide each year, (2) the health of those affected over the long term warrants attention. Treated pulmonary tuberculosis (PTB) can lead to complications, including progressive loss of lung function, (3) persistent pulmonary symptoms (3) and chronic pulmonary aspergillosis (CPA). (4-6) Of the long-term sequelae of PTB, CPA is perhaps the most subtle, yet the most severe. (4-11) In the 1960s the Research Committee of the British Thoracic and Tuberculosis Association estimated the prevalence of CPA in patients who had a residual cavity of at least 2.5 cm on the chest radiograph following treatment for PTB. (9,12) It assessed more than 500 patients from 55 chest clinics twice--once about 12 months after the sputum became negative for acid fast bacilli, (12) and again three years later? Remarkably, 25% of the patients had detectable Aspergillus precipitins in blood and both precipitins and radiological features of an aspergilloma were detectable in 14% at 12 months and in 22% at 3-4 years. PTB and CPA present with similar symptoms. This, combined with inadequate facilities for testing for immunoglobulin G (IgG) antibodies (precipitins) against A. fumigatus in many places, probably results in the underdiagnosis of CPA both at initial presentation (13) and following treatment for PTB. For example, in early case series of people with respiratory illness and negative acid fast bacillus (AFB) sputum smears in sub-Saharan Africa, A. fumigatus was among the pathogens identified. (14) CPA is an important differential diagnosis of what appears to be smear-negative tuberculosis.

CPA occurs in various forms: simple aspergilloma, chronic cavitary pulmonary aspergillosis and chronic fibrosing pulmonary aspergillosis, both with and without an aspergilloma. (4) Unlike invasive aspergillosis, CPA occurs in immunocompetent patients. Morbidity is considerable and is marked by both systemic and respiratory symptoms and haemoptysis. (7,8) Weight loss, profound fatigue, severe shortness of breath and life-threatening haemoptysis are common. Progressive pulmonary fibrosis and loss of lung function, also common, could partly account for the unexplained loss of lung function in these patients. Even when treated, CPA has a case fatality rate of 20-33% in the short-term and of 50% over a span of 5 years. (5,8)

The country-specific PTB statistics and mortality rates published by the World Health Organization (WHO) (15) make it possible to estimate the burden of chronic sequelae after treatment for PTB. Our objective was to use these published clinical and population data as inputs to model estimates of the likely burden of CPA related to PTB worldwide.

Methods

We developed a deterministic scenario model using Excel (Microsoft, Bellevue, United States of America). Fig. I shows our approach to estimating the adult burden of CPA in the largest countries of every WHO region. We started with WHO estimates of the number of new cases of PTB and of deaths from PTB (15) and assumed that the mortality figures quoted by the WHO were for the point 12 months after the diagnosis of PTB.

[FIGURE 1 OMITTED]

We searched the literature with the following questions in mind: (i) What is the frequency of pulmonary cavitation after completion of the treatment for PTB? (ii) How common is CPA following PTB? (iii) Are there any radiological risk factors (such as cavitation) for CPA? (iv) What is the range of the 12-month survival for PTB (to estimate the numbers at risk of developing CPA development)? and (v) What is the range of the 12-month survival for CPA (to estimate attrition and convert incidence to period prevalence)? We initially adopted a systematic search strategy but quickly realized that the literature was limited and that scoping reviews for all five questions were more appropriate. …

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.