Background: Midodrine and fludrocortisone are considered the first-line pharmacologic treatments for orthostatic hypotension (OH). Although OH is thought to require long-term therapy, it is unknown how long patients remain on treatment ("persistence").

Methods: We assembled a retrospective cohort of patients with OH aged ≥ 50 years enrolled in Tennessee Medicaid (1996-2008), and identified new episodes of midodrine and fludrocortisone use. Follow-up continued from the first medication fill through treatment discontinuation (90 days without medication), change in treatment, death, hospitalization, and loss of enrollment or study end. We compared persistence on treatment using Cox regression models and fludrocortisone as reference. Covariates included demographics, healthcare utilization measurements and co-morbidities.

Results: We identified 1704 OH patients, who initiated 1767 episodes of fludrocortisone (1103) or midodrine (664) use. The median age was 69 years, 53% were female and 80% were white. During 738 person years of follow-up, episodes of use ended because of treatment discontinuation in 467 (27% fludrocortisone, 25% midodrine); treatment change in 72 (3% fludrocortisone, 6% midodrine) and death in 53 (3% fludrocortisone, 2% midodrine). Overall median persistence on fludrocortisone and midodrine was 254 (IQR: 119-783) and 259 (IQR: 119-807) days, respectively. The adjusted hazard ratio (aHR) for overall non-persistence on midodrine compared to fludrocortisone was 1.07 (95% CI: 0.90-1.28).

Conclusions: Overall duration of OH treatment with first-line medications was short, and similar for fludrocortisone and midodrine. Further research is warranted to determine the causes of this low persistence. (Words#234).