Point of care HbA_1c level for diabetes mellitus management and its accuracy among tuberculosis patients: a study in four countries

Abstract

on behalf of the TANDEM consortium (members listed in full in submitted excel 9 spreadsheet) 10 11 1. Population Summary 48Background 49 Diabetes (DM) is common among tuberculosis (TB) patients and often undiagnosed or poorly 50 controlled. We compared point of care (POC) with laboratory glycated haemoglobin (HbA1c) tests 51 among newly diagnosed TB patients to assess POC test accuracy, safety, and acceptability in settings 52where immediate access to DM services may be difficult. 53 Methods 54We measured POC and accredited laboratory HbA1c (HPLC method) in 1942 TB patients aged over 18, 55 recruited from Peru, Romania, Indonesia, and South Africa. We calculated overall agreement and 56 individual variation (mean ± 2 standard deviations); stratified by country, age, sex, body mass index 57 (BMI), HbA1c level and comorbidities (anaemia, human immunodeficiency virus (HIV)). We used an 58 error grid approach to identify disagreement that could raise significant concerns. 59 Results 60Overall mean POC HbA1c values were modestly greater than laboratory HbA1c by 0.14% units (95% 61 confidence intervals 0.11 to 0.18), but there was a substantial discrepancy for those with severe 62 anaemia (1.07% HbA1c, 95%CI 0.67 to 1.46). For 89.6% of 1942 patients, both values indicated the 63 same DM status (no DM; HbA1c <6.5%) or had acceptable deviation (relative difference <6%). 64 Individual agreement was variable, with POC values up to 1.84% units higher or 1.56% lower. For a 65 minority, use of POC HbA1c alone could result in error leading to potential over-treatment (n=40, 2.1%) 66 or under treatment (n=1, 0.05%). The remainder had moderate disagreement, less likely to influence 67 clinical decisions. 68 Conclusion 69 POC HbA1c is pragmatic and sufficiently accurate to screen for hyperglycaemia and DM risk among TB 70 patients. 71 72 73 74 POC HbA1c (analysed using Hemocue® HbA1c 501 Analyser)[34] was collected during the participants' 131 clinic visits, and within 72 hours after TB diagnosis. In Romania, HemoCue® was not available so the 132 QuoTest[35] HbA1c Analyser QTD (by EKF Diagnostics) was substituted for Hemocue®. Laboratory 133 HbA1c was estimated from venous blood sample collection taken at the same time as the POC test. 134 All laboratory HbA1c samples were analysed using the HPLC method as per WHO guidelines and were 135 carried out in an accredited laboratory with NGSP certification[36]. 136 Consent and ethical approval 137

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

“…It has been reported that severe anaemia can affect HbA1c, with possible over-estimation in iron deficiency anaemia and under-estimation with haemolytic anaemia 44 . In the small number of those with severe anaemia in the study comparing POC HbA1c with laboratory HbA1c, the POC test showed a mean difference of +1.1% 43 . The amount of missing information for HIV status is a limitation, especially for the rural sites.…”

“…This study did not rely on routine testing or self-reporting of diabetes or undernutrition and used trained research nurses to conduct all assessments and anthropometry. Although the use of a single POC test for HbA1c is not currently recommended for diabetes diagnosis by regulatory bodies, its agreement with accredited laboratory measurement using high performance liquid chromatography in persons with TB has recently been shown to be high, with minimal effects on clinical misclassification 43 . However, the higher proportion of participants with severe anaemia in our setting may have resulted in some misclassification in this group.…”

High prevalence and heterogeneity of Dysglycemia in patients with tuberculosis from Peru: a prospective cohort study

“…In our study, we found that all TB-DM people and a good proportion of TB-preDM patients were anemic. There is evidence supporting the idea that performance of HbA1c in detecting dysglycemia is affected by occurrence of anemia [35]. Herein, we analyzed the relationship between HbA1c and anemia and found no clear influence in the test performance to diagnose DM.…”

The Interaction of Diabetes and Tuberculosis: Translating Research to Policy and Practice

“…Diabetes seems to increase the risk of TB recurrence and also appears to be associated with a doubling of the risk of identification of multi-drug resistant TB [36]. Poorly controlled diabetes (as measured by high HbA1c or fasting blood glucose) is associated with increased TB susceptibility and might also worsen TB treatment outcomes (see Figure 1).…”