A team led by Andrew Holman, from Pacific Rheumatology Research in Renton, Washington, studied 25 patients with rheumatoid arthritis and eight with psoriatic arthritis who were treated with etanercept or adalimumab for 52 weeks.
The participants were assessed for parasympathetic, sympathetic, total power and tension index measures of autonomic reactivity at baseline, with clinical response determined at weeks 6, 12, 26 and 52.
"Elevated sympathetic and decreased parasympathetic tone reduces the usual variability of heart rate to make it more constant," the researchers explain in the journal Autonomic Neuroscience: Basic and Clinical.
The average age of the patients was 48 years, and the average disease duration was 7.6 years. Anti-TNF therapy was continued for 52 weeks in 64% of the patients.
A poor response to anti-TNF therapy was linked to low parasympathetic and total power measures and to high sympathetic and tension index measures.
All HRV assessments except the sympathetic measure significantly predicted improvements on the American College of Rheumatology criteria of 20%, 50% and 70% at week 52, and as early as week 6 for some measures.
In contrast, only parasympathetic and tension index measures predicted changes in Disease Activity Score including a 28-joint count.
The team writes: "Using a rapid and convenient assessment tool, these results suggest that baseline autonomic status may influence outcome and disease activity at 52 weeks and as early as 6 weeks."