TBscore II: refining and validating a simple clinical score for treatment monitoring of patients with pulmonary tuberculosis

Background: The TBscore, based on simple signs and symptoms, was introduced to predict unsuccessful outcome in tuberculosis patients on treatment. A recent inter-observer variation study showed profound variation in some variables. Further, some variables depend on a physician assessing them, making the score less applicable. The aim of the present study was to simplify the TBscore. Methods: Inter-observer variation assessment and exploratory factor analysis were combined to develop a simplifi ed score, the TBscore II. To validate TBscore II we assessed the association between start score and failure (i.e. death or treatment failure), responsiveness using Cohen ’ s effect size, and the relationship between severity class at treatment start and a decrease 25% in score from the start until the end of the second treatment month and subsequent mortality. Results: We analyzed data from 1070 Guinean (2003 – 2012) and 432 Ethiopian (2007 – 2012) pulmonary tuberculosis patients. For the refi ned score, items with less than substantial agreement ( κ 0.6) and/or not associated with the underlying constructs were excluded. Items kept were: cough, dyspnea, chest pain, anemia, body mass index (BMI) 18 kg/m 2 , BMI 16 kg/m 2 , mid upper arm circumference (MUAC) 220 mm, and MUAC 200 mm. The effect sizes for the change between the start of treatment and the 2-month follow-up were 0.51 in Guinea-Bissau and 0.68 in Ethiopia, and for the change between the start of treatment and the end of treatment were 0.68 in Guinea-Bissau and 0.74 in Ethiopia. Severity class placement at treatment start predicted failure ( p 0.001 Guinea-Bissau, p 0.208 Ethiopia). Inability to decrease at least 25% in score was associated with a higher failure rate during the remaining 4 months of treatment ( p 0.063 Guinea-Bissau, p 0.008 Ethiopia). Conclusion: The TBscore II could be a useful monitoring tool, aiding triage at the beginning of treatment and during treatment.