A proof-of-concept study with a limited sample of RA patients has shown that individuals with poor HRV profiles may exhibit an inadequate response to anti-tumor necrosis factor-alpha agents.18 Additionally, an economic exploratory analysis19 suggests that HRV testing and ANS optimisation prior to initiating biologics in refractory RA patients could be cost-effective. The gene discussed is TNF; the disease is rheumatoid arthritis.