OBJECTIVES: Ultrasound technology had considerable developments, becoming a safe and efficient alternative to complement the diagnosis of rheumatoid arthritis (RA). We aimed to evaluate the cost and effectiveness of ultrasound in the correct diagnosis of seronegative patients with presumptive RA in a real life setting.

METHODS: We included patients with presumptive RA but negative rheumatoid factor and anti-CCP. The patient was evaluated by a rheumatologist expert in ultrasound; US studies were carried out with a Esaote MyLab Seven® US equipment. We calculated means and standard deviations for continuous variables and categorical variables were presented as percentages. We calculated the costs for each ultrasound and projected the cost-savings according to RA diagnosis. Costs were presented in US dollars at the official rate of exchange for December 2017.

RESULTS: We included 120 patients with presumptive RA, 50% were female. Mean age was 58 ±13 years. We found that 25% of patients had erosions in hands, 39% had synovitis and 30% had power Doppler. Also, 2% had erosions in feet, 7% had synovitis and 6% had power Doppler. The costs for ultrasound per patient was USD$37, and for all patients USD$4.400. According to the cost savings, we avoided the use of MRI of hands and feet with a cost of USD$38.400 (USD$320 per/patient). Thus, we confirmed the diagnosis of RA in 50% of our patients. In the remaining patients we avoided the use of treatment for presumptive seronegative RA ranging between USD$64.140 (mean price for conventional DMARDs) to USD$507.480 (mean price for biological DMARDs).

CONCLUSIONS: In a real life-setting, ultrasound has demonstrated to be a useful and low- cost tool that can complement clinical findings when the diagnosis for RA is complex. As was demonstrated, ultrasound can save resources to health systems due to the non-usage of expensive pharmacological therapy for RA.