RESUMEN
OBJECTIVE: To determine the value of salivary cortisol concentrations in predicting the efficacy of sleep-promoting treatment in children with postural tachycardia syndrome (POTS). STUDY DESIGN: This prospective study involved 40 children with POTS and 20 healthy children (controls). POTS was diagnosed using the head-up or head-up tilt test. Patients with POTS received a sleep-promoting treatment: >8 hours of sleep every night and a midday nap in an appropriate environment; no drinking water or exercising before bedtime; and urination before bedtime. The Pittsburgh Sleep Quality Index was used to evaluate sleep quality, and symptom scores were used to assess POTS severity. Salivary samples were collected upon awakening, 30 minutes after awakening, at 12:00 p.m., 4:00 p.m., and 8:00 p.m., and at bedtime before treatment. Enzyme-linked immunosorbent assay was used to measure salivary cortisol concentrations. RESULTS: Cortisol concentrations were significantly higher in patients with POTS than in the controls at all time points (P < .05 for all). PSQI scores were significantly higher in patients with POTS (7.2 ± 3.0) than in the controls (1.35 ± 1.39; t = -10.370, P <.001). Salivary cortisol concentrations at awakening were significantly higher in responders than in nonresponders (4.83 ± 0.73 vs 4.05 ± 0.79 ng/mL, t = -3.197, P = .003). The area under the receiver operating characteristic curve was 75.8%, (95% CI 59.3%-92%). Cut-off at-awakening salivary cortisol concentrations of >4.1 ng/mL yielded 83.3% sensitivity and 68.7% specificity in predicting therapeutic efficacy. CONCLUSIONS: At-awakening salivary cortisol concentrations may predict the efficacy of sleep-promoting treatment in patients with POTS.