BackgroundTo evaluate baseline hemoglobin (Hb) and radiographic progression over time in patients enrolled in the Brigham and Women’s Rheumatoid Arthritis Sequential Study (BRASS) registry.MethodsThe BRASS is a prospective observational registry of patients with rheumatoid arthritis. BRASS Hb data and total sharp score data were matched with the main BRASS patients. Hb at baseline was categorized per the World Health Organization guidelines. Mean Hb, mean total sharp score, and mean changes over time from baseline to month 120 were summarized (overall, by low/normal Hb, and by current medication at baseline). All analyses were descriptive.ResultsOut of the total (N= 1114) rheumatoid arthritis patients included in the analysis, patients with low Hb at baseline (n= 224 [20%]) had longer disease duration and higher disease activity and reported more pain compared with patients with normal Hb at baseline (n= 890 [80%]). Patients with low Hb at baseline continued to have lower Hb than patients with normal Hb throughout 10 years; although, on average, patients in the low Hb subgroup exhibited a steady increase in Hb levels. A larger increase in total sharp score over time was observed for patients with low Hb than for patients with normal Hb. No meaningful differences potentially attributable to medication at baseline were detected.ConclusionsPatients with low Hb levels at baseline tended to have increased radiographic progression as measured by total sharp score compared with patients with rheumatoid arthritis having normal Hb levels. Patients with low Hb experienced sustained improvements in Hb levels over time, regardless of the class of medication used.Trial registrationClinicalTrials.gov NCT01793103.Supplementary InformationThe online version contains supplementary material available at 10.1186/s13075-023-03068-w.