OBJECTIVES: To determine health outcomes of diagnosis and on-time treatment of an acquired thrombotic thrombocytopenic purpura (aTTP) episode.

METHODS: A partitioned survival model with two health states (survival & death) was developed for expected clinical outcomes among patients with no-diagnosis versus diagnosis of aTTP and on-time treatment with plasma exchange initiated within 24 hours after diagnosis versus delayed treatment starting on day 2 up to day 5.

Outcomes correspond to mortality rates within 30 days, platelet normalization within 10 days, and number of patients without exacerbations or relapses within one year after an aTTP episode. Comparison scenarios were: 1) diagnosis vs. no-diagnosis and 2) on-time treatment vs. delayed treatment.

The analysis modelled a hypothetical cohort of 100 patients with an aTTP episode. Clinical data for health outcomes was obtained from published literature.

RESULTS: For the comparison between diagnosis and no-diagnosis, mortality within 30 days was 3 and 68 deaths, respectively; platelet normalization was achieved within 10 days in 86 and 0 patients, respectively.

For the comparison between on-time and delayed treatment, mortality grew from 3 deaths with on-time treatment to 21, 27, 32 and 36 deaths when treatment started on day 2, 3, 4 and 5 respectively. Delaying treatment initiation by one day after diagnosis reduced the number of patients with normalized platelet levels, no exacerbations, or relapses.

CONCLUSIONS: Since an aTTP episode is an acute life-threatening event, mortality rates are critical outcomes. This study demonstrates that the main benefit between diagnosis and no-diagnosis is reduced mortality. This suggests that institutions should reinforce training to consider this diagnosis in patients with hemolytic anemia and thrombocytopenia to improve diagnosis rates. Additionally, early treatment is associated with better clinical outcomes, including survival and number of exacerbations and relapses. Therefore, after correctly diagnosing an aTTP episode, prompt treatment will allow for the best clinical and health outcomes.