Inter-Observer Variability in the Detection and Interpretation of Chest X-Ray Anomalies in Adults in an Endemic Tuberculosis Area

Purpose: To assess the inter-observer agreement in reading adults chest radiographs (CXR) and determine the effectiveness of observers in radiographic diagnosis of pulmonary tuberculosis (PTB) in a tuberculosis endemic area. Methods: A quasi-observational study was conducted in the Pneumology Department of Yaounde Jamot Hospital (Cameroon) from January to March 2014. This included six observers (two chest physicians, two radiologists, two end-training residents in medical imaging) and 47 frontal CXRs (4 of diffuse interstitial lung disease, 6 normal, 7 of lung cancers, 7 of bacterial pneumonia, 23 of PTB). The sample size was calculated on the basis of an expected 0.47 Kappa with a spread of 0.13 (α = 5%, CI = 95%) for six observers and five diagnostic items. The analysis of concordance was focused on the detection of nodules, cavitary lesions, pleural effusion, adenomegaly and diagnosis of PTB and lung cancer. These intervals of kappa coefficient were considered: discordance (0.81). Results: The average score for the detection of caverns was the highest (58.3%) followed by that of the correct diagnosis of tuberculosis (49.3%). Pneumologists had the highest proportions of correct diagnosis of tuberculosis (69.6% and 73.9%) and better inter-observer agreement (k = 0.71) for PTB diagnosis. Observers were more in agreement for the detection of nodules (0.32 - 0.74), adenomegalies (0.43 - 0.69), and for the diagnosis of cancer (0.22 - 1) than for the diagnosis of tuberculosis (0.19 - 0.71). Disagreements were more frequent for the detection of pleural effusions (-0.08 - 0.73). Conclusion: The inter-observer agreement varies with the type of lesions and diagnosis. Pneumologists were most effective for the diagnosis of pulmonary tuberculosis. Observers were more in agreement for the detection of nodules and the diagnosis of cancer than for the diagnosis of pulmonary tuberculosis.

Spirometric Reference Equations for Semi-Urban and Urban Bantu Cameroonians

Background: Spirometric reference values vary substantially across ethnic groups, and remain largely poorly characterized among Africans. We derived spirometric reference equations for adult Cameroonians and compared their performance with those derived from other ethnic groups. Methods: Spirometric variables according to the American Thoracic Society/European Respiratory Society 2005 guidelines were acquired in voluntary healthy non-smoker subjects in Yaounde (Capital City) and Foumbot (semi-urban area in West Region), in Cameroon during November 2011 to January 2012 (Yaounde) and August 2012 (Foumbot). Reference equations were derived separately for men and women from multiple linear regressions. Results: A total of 411 subjects (206 men) met the inclusion criteria. The mean age was 39.5 ± 16.1 years (min - max: 18 - 85 years) for men and 39.2 ± 14.1 years (18 - 90 years) for women. Age and height were the only variables significantly associated with spirometric values in the final linear regression models. Derived reference values were lower than those derived from Global Lung Initiative 2012 equations for different ethnic groups, except for the forced expiratory volume in 1 second/forced vital capacity ratio (FEV1/FVC ratio). The mean FEV1/FVC ratio was 0.88 ± 0.07 for Cameroonian men and 0.89 ± 0.07 for Cameroonian women. Variations in the performance of derived models in bootstrap internal validation were marginal. Conclusion: This study highlights the importance of deriving specific predictive equations for each ethnic group. The use of adjustment factors applied to Caucasian equations when compared with the values derived in our study leads to an overestimation of the values for FEV1 and FVC.