The impact of tuberculosis on health utility: a longitudinal cohort study

To estimate health utility derived from the Short Form-36 (SF-36) questionnaire and Standard Gamble instrument for persons diagnosed and treated for tuberculosis (TB) disease, those diagnosed and treated for latent TB infection (LTBI), and those screened but not treated for TB disease or LTBI over the year following their diagnosis/initial assessment. Participants were recruited at two Montreal hospitals (2008-2011) and completed the SF-36 and Standard Gamble at baseline and at follow-up visits 1, 2, 4, 6, 9, and 12 months thereafter. SF-6D health utility scores were derived from SF-36 responses. Linear mixed models were used to compare mean health utility at each evaluation and changes in health utility between participants treated for TB disease, those treated for LTBI, and those in the control group. Of the 263 participants, 48 were treated for TB disease, 105 for LTBI, and 110 were control participants. Fifty-four percent were women, mean age was 35 years, and 90 % were foreign-born. Participants treated for TB disease reported worse health utility compared with control participants at the baseline visit (mean SF-6D: 0.69 vs. 0.81; mean Standard Gamble: 0.64 vs. 0.96). They reported successive improvement at months 1 and 2 that was then sustained throughout follow-up. Health utility reported by participants treated for LTBI and control participants was comparable throughout the study. Treatment for TB disease had a substantial negative impact on health utility, particularly during the first 2 months of treatment. However, treatment for LTBI did not have a substantial impact.