Time to Progress Through the Latent Tuberculosis Infection Care Cascade in Primary Care

Although treatment of latent tuberculosis infection (LTBI) is highly effective for preventing tuberculosis disease, diagnosis requires several steps. A care cascade is a helpful framework for identifying the clinical events necessary for successful LTBI treatment, yet the timing of progression through these events is poorly characterized. We calculated the timing of an LTBI care cascade and assessed whether timing was associated with increased cascade progression.

We conducted an observational study through the Tuberculosis Epidemiologic Studies Consortium using electronic health records to calculate the timing of steps in the LTBI care cascade in the United States from 2020 through 2022 (N = 693 254 patients). Using receiver operating characteristic curves, we identified optimal maximum times (OMTs) associated with cascade progression, and we calculated risk ratios to compare outcomes between patients who advanced above and below OMTs.

The median (IQR) time from most recent test order to test result was 3 (1-4) days; from most recent test order to imaging order, 7 (4-18) days; from imaging order to treatment prescription, 17 (6-40) days; from treatment prescription to treatment start, 0 (0-1) days; from treatment start to treatment completion, 116 (103-120) days; and for the entire cascade, 150 (133-189) days. Risk ratios for cascade progression ranged from 1.10 to 2.81, demonstrating that patients completing steps below the OMTs showed marginally higher likelihoods of progression through the care cascade.

These findings highlight the importance of sustained follow-up and caution against early classification of patients as lost to care, supporting public health strategies for health systems, programs, health care providers, and care navigators that emphasize long-term engagement to maximize the preventive effect of LTBI treatment.