Pattern of abnormalities amongst chest X‐rays of adults undergoing computer‐assisted digital chest X‐ray screening for tuberculosis in Peri‐Urban Blantyre, Malawi: A cross‐sectional study

Abstract

Background The prevalence of diseases other than tuberculosis (TB) detected during chest X‐ray screening is poorly described in sub‐Saharan Africa. Computer‐assisted digital chest X‐ray technology is available for TB screening and has the potential to be a screening tool for non‐communicable diseases as well. Low‐ and middle‐income countries are in a transition period where the burden of non‐communicable diseases is increasing, but health systems are mainly focused on addressing infectious diseases. Methods Participants were adults undergoing computer‐assisted chest X‐ray screening for tuberculosis in a community‐wide tuberculosis prevalence survey in Blantyre, Malawi. Adults with abnormal radiographs by field radiographer interpretation were evaluated by a physician in a community‐based clinic. X‐ray classifications were compared to classifications of a random sample of normal chest X‐rays by radiographer interpretation. Radiographic features were classified using WHO Integrated Management for Adult Illnesses (IMAI) guidelines. All radiographs taken at the screening tent were analysed by the Qure.ai qXR v2.0 software. Results 5% (648/13,490) of adults who underwent chest radiography were identified to have an abnormal chest X‐ray by the radiographer. 387 (59.7%) of the participants attended the X‐ray clinic, and another 387 randomly sampled normal X‐rays were available for comparison. Participants who were referred to the community clinic had a significantly higher HIV prevalence than those who had been identified to have a normal CXR by the field radiographer (90 [23.3%] vs. 43 [11.1%] p‐value < 0.001). The commonest radiographic finding was cardiomegaly (20.7%, 95% CI 18.0–23.7). One in five (81/387) chest X‐rays were misclassified by the radiographer. The overall mean Qure.ai qXR v2.0 score for all reviewed X‐rays was 0.23 (SD 0.20). There was a high concordance of cardiomegaly classification between the physician and the computer‐assisted software (109/118, 92.4%). Conclusion There is a high burden of cardiomegaly on a chest X‐ray at a community level, much of which is in patients with diabetes, heart disease and high blood pressure. Cardiomegaly on chest X‐ray may be a potential tool for screening for cardiovascular NCDs at the primary care level as well as in the community.

Assessment of non-tuberculosis abnormalities on digital chest x-rays with high CAD4TB scores from a tuberculosis prevalence survey in Zambia and South Africa

“…This prevalence was higher than what was reported in a study that was done in Kenya which reported a prevalence of 5.7% for minor pleural effusion/thickening/calcification [ 15 ]. Our findings were also higher than what was reported in another study in Malawi which reported a prevalence of 1% for pleural effusions [ 16 ]. The current study might have reported a higher prevalence of pleural effusions because Zambia and South Africa are among the top 30 countries with the highest TB burden globally [ 32 ] and pleural effusion is a common primary or secondary clinical complication of many disorders including TB, heart failure, bacterial pneumonia, liver cirrhosis, hypoalbuminemia, cancer, emphysema and pulmonary embolism [ 33 , 34 ].…”

“…In the current study, cardiomegaly was reported at 5% as the second most prevalent non-TB abnormality. This prevalence was much lower than what was found in the Kenya and Malawian studies [ 15 , 16 ]. The Malawian study reported a prevalence of 20.7% for cardiomegaly while the Kenyan study reported a prevalence of 23.1% for cardiomegaly.…”

“…Studies that have been done on CXRs in other Sub-Saharan African countries have reported a high prevalence of non-TB abnormalities such as cardiomegaly with heart failure, chronic obstructive lung disease (COPD), and post-TB lung changes [ 15 , 16 ]. These studies investigated non-TB abnormalities on all abnormal CXRs irrespective of the CAD scores and TB history.…”

Incidental radiological findings during clinical tuberculosis screening in Lesotho and South Africa: a case series

“…When screening for TB, users of AI software need to be aware that other chest pathologies are likely to be as prevalent as, or more prevalent than, active TB [ 22 ]. However, non­-TB CXR abnormalities detected during CXR screening remain poorly characterized in the sub-Saharan African setting, with only minimal literature [ 22 , 23 ]. There is no structured system for the detection and referral of such patients [ 24 , 25 ].…”

“…In a retrospective analysis of X-ray images from the 2016 Kenya TB Prevalence Survey, a large number of patients with non-TB-related abnormalities were identified, with cardiac and pulmonary diseases accounting for 66% of the non-TB abnormalities in this setting [ 22 ]. In 2021, a cross-sectional study in Malawi studying the range of CXR abnormalities during a TB screening reported a high prevalence of non-tuberculous abnormalities found by the CXR-analyzing physician, the most recurrent abnormality being cardiomegaly with 20.7% (95% CI 18.0–23.7%) [ 23 ]. In our TB TRIAGE + ACCURACY study [ 16 ] among presumptive TB cases, 6.6% of CXR showed non-TB-related CXR abnormalities, as compared with 25.6% of CXR presenting abnormalities categorized as possible TB or highly suspicious for TB.…”