Lupus & antiphospholipid syndrome
Real‐World Longitudinal Data on the Impact of Hydroxychloroquine Blood Level Monitoring on Lupus Outcomes: Results of a Prospective Longitudinal Cohort Study
Authors' conclusion
HCQ blood level monitoring could improve SLE control, particularly in patients with estimated glomerular filtration rate ≤75, and enable optimal HCQ use.
Study context
- Population
- Patients with systemic lupus erythematosus (SLE) on weight-based hydroxychloroquine (HCQ) dosing in a prospective SLE cohort (baseline mean age 47 years; 91% female; 66% White)
- Participants
- 247 patients962 visits
- Exposure
- HCQ blood levels: very low and subtherapeutic vs therapeutic levels
- Outcome
- Active SLE (and flares) over time by HCQ blood levels
- Follow-up
- Over time
Methodological detailslongitudinal, generalized linear mixed models, within- and between-subject decomposition models
- Longitudinal
- Generalized linear mixed models
- Within- and between-subject decomposition models
Main finding
As reported in the abstract
Active SLE over time
Fold higher odds
6.7
Very low
Fold higher odds
2.6
Subtherapeutic
Observational data: associations, not effects.
Further findings
Individual patient level: per 100 ng/mL increase in HCQ levels at each visit
- Lower odds of active SLE
- 33%
- Lower odds of flares
- 22%
HCQ levels by kidney function · over time
- Patients with kidney function ≤75 mL/min/1.73m2 had supratherapeutic levels over time despite receiving 5 mg/kg/day
Baseline HCQ levels and dose
- Subtherapeutic HCQ levels (<750 ng/mL)
- 45%
- HCQ dose of ≤5 mg/kg/day
- 79%
Original publication
Real‐World Longitudinal Data on the Impact of Hydroxychloroquine Blood Level Monitoring on Lupus Outcomes: Results of a Prospective Longitudinal Cohort Study. Arthritis Care Res (Hoboken). Published 3 May 2026. doi:10.
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