Accuracy of diabetes screening methods used for people with tuberculosis, Indonesia, Peru, Romania, South Africa

Abstract

ObjectiveTo evaluate the performance of diagnostic tools for diabetes mellitus, including laboratory methods and clinical risk scores, in newly-diagnosed pulmonary tuberculosis patients from four middle-income countries.MethodsIn a multicentre, prospective study, we recruited 2185 patients with pulmonary tuberculosis from sites in Indonesia, Peru, Romania and South Africa from January 2014 to September 2016. Using laboratory-measured glycated haemoglobin (HbA1c) as the gold standard, we measured the diagnostic accuracy of random plasma glucose, point-of-care HbA1c, fasting blood glucose, urine dipstick, published and newly derived diabetes mellitus risk scores and anthropometric measurements. We also analysed combinations of tests, including a two-step test using point-of-care HbA1cwhen initial random plasma glucose was ≥ 6.1 mmol/L.FindingsThe overall crude prevalence of diabetes mellitus among newly diagnosed tuberculosis patients was 283/2185 (13.0%; 95% confidence interval, CI: 11.6–14.4). The marker with the best diagnostic accuracy was point-of-care HbA1c (area under receiver operating characteristic curve: 0.81; 95% CI: 0.75–0.86). A risk score derived using age, point-of-care HbA1c and random plasma glucose had the best overall diagnostic accuracy (area under curve: 0.85; 95% CI: 0.81–0.90). There was substantial heterogeneity between sites for all markers, but the two-step combination test performed well in Indonesia and Peru.ConclusionRandom plasma glucose followed by point-of-care HbA1c testing can accurately diagnose diabetes in tuberculosis patients, particularly those with substantial hyperglycaemia, while reducing the need for more expensive point-of-care HbA1c testing. Risk scores with or without biochemical data may be useful but require validation.

Patterns and predictors of co-morbidities in Tuberculosis: A cross-sectional study in the Philippines

“…However, unlike recent data from a multi-country study investigating diabetes in TB (the TANDEM study), we did not observe an association between diabetes and previous TB or with smear positive cases 31 . The distribution of HbA1c values for our diabetic population (new and previously diagnosed cases) was also similar to that from the Indonesian TANDEM study population, in whom a single point of care (POC) HbA1c test was shown to have high sensitivity and specificity to detect new diabetes cases, adding confidence to our diagnoses of diabetes using this single POC measurement 41 .…”

“…We thus investigated how, in resource-limited settings, waist-to-hip ratio might be useful as a screening tool for prioritising individuals for diabetes testing and observed a high sensitivity of 87% for a single cut-off for both sexes, supporting its potential use, at least in the Filipino context. Mean waist to hip ratio was also significantly increased in the TANDEM study, and most significantly in Indonesia 31 , although neither waist to hip ratio or waist circumference were included in the final multicountry predictive risk score for diabetes in persons with TB 41 .…”

Diabetes Mellitus Among Pulmonary Tuberculosis Patients From 4 Tuberculosis-endemic Countries: The TANDEM Study

“…At 21%, the prevalence of intermediate hyperglycaemia ("pre-diabetes") identified in TB patients was higher than expected, although a rising prevalence of intermediate hyperglycaemia has been reported in LMICs [31]. This figure would have even been higher based on point-of-care HbA1c results [10], or use of the lower American Diabetes Supplementary Figure 1) [9]. The definition of intermediate hyperglycaemia itself is under scrutiny as DM only develops within 10 years in <50% of those identified with pre-DM based on a single FBG or HbA1c test [33], and uncertainty about the cut-point when using HbA1c.…”

“…We defined individuals with pulmonary TB if they initiated treatment at a local TB program, based on bacteriological (sputum smear, sputum culture or Xpert test), radiological and/or clinical evidence. Further details are published elsewhere [9,10] and are freely available in online appendices [8].…”

“…Intermediate hyperglycaemia (or 'pre-diabetes'; raised blood glucose or HbA1c above normal, but below the threshold for identifying DM) was defined as patients with a single measurement of either FBG in the pre-DM range (6.1-7.0 mmol/l) or HbA1c in the intermediate range (6.0-6.4%) [12](See Appendix 1). Evaluation of the performance of these laboratory tests for diagnosis of DM in TB patients in a TANDEM cohort has recently been published [9].…”