Hydroxychloroquine in lupus or rheumatoid arthritis pregnancy and risk of major congenital malformations: a population-based cohort study.

OBJECTIVES: To assess the infant risk of major congenital malformations (MCM) associated with first-trimester exposure to hydroxychloroquine (HCQ) among mothers with systemic lupus erythematosus (SLE) or rheumatoid arthritis (RA). METHODS: This population-based cohort study utilised Swedish nationwide registers and included all singleton births (2006-2021) among individuals with prevalent SLE or RA in Sweden. The exposure was filling ≥1 HCQ prescription during the first trimester. The outcome was infant MCM within one year of birth. Inverse probability of treatment weighting was applied to adjust for potential confounders (e.g. maternal smoking, body mass index, pregestational diabetes, and corticosteroids). Modified Poisson regression models with robust variance estimated risk ratios and 95% confidence intervals (RR 95%CI). RESULTS: We included 1,007 births (453 exposed) and 2,500 births (144 exposed) in the SLE and RA cohorts, respectively. The MCM risks in the SLE overall cohort, exposed, and unexposed groups were 3.6%, 3.7%, and 3.4%, respectively. The corresponding figures in the RA cohort were 4.4%, 5.6%, and 4.3%, respectively. The adjusted RRs (95%CI) were 1.29 (0.65-2.56) in the SLE cohort, 1.32 (0.56-3.13) in the RA cohort, and 1.30 (0.76-2.23) in the pooled analysis. The adjusted risk difference (exposed vs unexposed) was small (0.9% in SLE and 1.3% in RA). Sensitivity analyses examining different exposure and outcome windows yielded similar findings. CONCLUSIONS: First-trimester exposure to HCQ was not associated with a significantly increased risk of MCM. HCQ's benefits may outweigh the risks in managing SLE or RA during pregnancy.

The Problem of Pain in Rheumatology: Variations in Case Definitions Derived From Chronic Pain Phenotyping Algorithms Using Electronic Health Records.

OBJECTIVE: The aim of this study was to investigate and compare different case definitions for chronic pain to provide estimates of possible misclassification when researchers are limited by available electronic health record and administrative claims data, allowing for greater precision in case definitions. METHODS: We compared the prevalence of different case definitions for chronic pain (N = 3042) in patients with autoimmune rheumatic diseases. We estimated the prevalence of chronic pain based on 15 unique combinations of pain scores, diagnostic codes, analgesic medications, and pain interventions. RESULTS: Chronic pain prevalence was lowest in unimodal pain phenotyping algorithms: 15% using analgesic medications, 18% using pain scores, 21% using pain diagnostic codes, and 22% using pain interventions. In comparison, the prevalence using a well-validated phenotyping algorithm was 37%. The prevalence of chronic pain also increased with the increasing number (bimodal to quadrimodal) of phenotyping algorithms that comprised the multimodal phenotyping algorithms. The highest estimated chronic pain prevalence (47%) was the multimodal phenotyping algorithm that combined pain scores, diagnostic codes, analgesic medications, and pain interventions. However, this quadrimodal phenotyping algorithm yielded a 10% overestimation of chronic pain compared to the well-validated algorithm. CONCLUSION: This is the first empirical study to our knowledge that shows that established common modes of phenotyping chronic pain can lead to substantially varying estimates of the number of patients with chronic pain. These findings can be a reference for biases in case definitions for chronic pain and could be used to estimate the extent of possible misclassifications or corrections in using datasets that cannot include specific data elements.

The Problem of Pain in Lupus: Epidemiological Profiles of Patients Attending Multidisciplinary Pain Clinics.

INTRODUCTION: Patients with systemic lupus erythematosus (SLE) bear a significant burden of pain. We aimed to identify factors that distinguish patients with SLE referred to comprehensive pain clinics and those who are not. Characterizing this patient population will identify unmet needs in SLE management and inform efforts to improve pain care in rheumatology. METHODS: Among patients with SLE with ≥2 rheumatology clinic visits in a large hospital system from 1998 to 2023 (n = 1319), we examined factors that distinguished those who had at least one visit to multidisciplinary pain clinics (n = 77, 5.8%) from those who did not have any visits (n = 1242, 94.2%) with a focus on biopsychosocial and socioeconomic characteristics. We extracted demographic data and ICD-9/ICD-10 codes from the EHR. RESULTS: Patients with SLE attending the pain clinics exhibited characteristics including average older age (mean age ± SD: 54.1 ± 17.9 vs. 48.4 ± 19.9), a higher likelihood of relying on public health insurance (50.7% vs. 34.2%), and a greater representation of Black patients (9.1% vs. 4.4%) compared to SLE patients not seen in pain clinics. Nearly all patients seen at the pain clinics presented with at least one chronic overlapping pain condition (96.1% vs. 58.6%), demonstrated a higher likelihood of having a mental health diagnosis (76.7% vs. 42.4%), and exhibited a greater number of comorbidities (mean ± SD: 6.0 ± 3.0 vs. 2.9 ± 2.6) compared to those not attending the pain clinic. CONCLUSION: We found notable sociodemographic and clinical differences between these patient populations. Patients presenting with multiple comorbidities might benefit from further pain screening and referral to pain clinics to provide comprehensive care, and earlier referral could mitigate the development and progression of multimorbidities.

Baseline factors associated with self-reported disease flares following COVID-19 vaccination among adults with systemic rheumatic disease: results from the COVID-19 global rheumatology alliance vaccine survey.

OBJECTIVE: To examine the frequency of, and risk factors for, disease flare following COVID-19 vaccination in patients with systemic rheumatic disease (SRD). METHODS: An international study was conducted from 2 April to 16 August 2021, using an online survey of 5619 adults with SRD for adverse events following COVID-19 vaccination, including flares of disease requiring a change in treatment. We examined risk factors identified a priori based on published associations with SRD activity and SARS-CoV-2 severity, including demographics, SRD type, comorbidities, vaccine type, cessation of immunosuppressive medications around vaccination and history of reactions to non-COVID-19 vaccines, using multivariable logistic regression. RESULTS: Flares requiring a change in treatment following COVID-19 vaccination were reported by 4.9% of patients. Compared with rheumatoid arthritis, certain SRD, including systemic lupus erythematosus (OR 1.51, 95% CI 1.03, 2.20), psoriatic arthritis (OR 1.95, 95% CI 1.20, 3.18) and polymyalgia rheumatica (OR 1.94, 95% CI 1.08, 2.48) were associated with higher odds of flare, while idiopathic inflammatory myopathies were associated with lower odds for flare (OR 0.54, 95% CI 0.31-0.96). The Oxford-AstraZeneca vaccine was associated with higher odds of flare relative to the Pfizer-BioNTech vaccine (OR 1.44, 95% CI 1.07, 1.95), as were a prior reaction to a non-COVID-19 vaccine (OR 2.50, 95% CI 1.76, 3.54) and female sex (OR 2.71, 95% CI 1.55, 4.72). CONCLUSION: SRD flares requiring changes in treatment following COVID-19 vaccination were uncommon in this large international study. Several potential risk factors, as well as differences by disease type, warrant further examination in prospective cohorts.

Subsequent risk of stillbirth, preterm birth, and small for gestational age: A cross-outcome analysis of adverse birth outcomes.

BACKGROUND: Stillbirth, preterm birth, and small for gestational age (SGA) birth have an increased recurrence risk. The occurrence of one of these biologically related outcomes could also increase the risk for another one of these outcomes in a subsequent pregnancy. OBJECTIVES: We assessed cross-outcome risks for subsequent stillbirth, preterm birth, and SGA. METHODS: We used live birth and fetal death records to identify singleton, sequential birth pairs in California (1997-2017). Stillbirth was defined as delivery at ≥20 weeks of gestation of a foetus that died in utero; preterm birth as live birth at 20-36 weeks; and small for gestational age as sex-specific birthweight <10th percentile for gestational age. Risk ratios (RR) were computed using modified Poisson regression and adjusted for potential confounders. Sensitivity analyses included analysing a cohort restricted to primiparous index births and using inverse-probability censoring weights. RESULTS: Of 3,108,532 birth pairs, 16,668 (0.5%), 260,596 (8.4%) and 331,109 (10.7%) of index births were stillborn, preterm and SGA, respectively. Among individuals with an index stillbirth, the adjusted RRs were 1.90 (95% confidence interval [CI] 1.83, 1.98) for subsequent preterm and 1.35 (95% CI 1.28, 1.41) for subsequent SGA. Among those with index preterm birth, the adjusted RRs were 2.02 (95% CI 1.92, 2.13) for stillbirth and 1.42 (95% CI 1.41, 1.44) for SGA. Among those with index SGA, the adjusted RRs were 1.54 (95% CI 1.46, 1.63) for stillbirth and 1.45 (95% CI 1.44, 1.47) for preterm birth. Similar results were reported for sensitivity analyses. CONCLUSIONS: Individuals experiencing stillbirth, preterm birth, or SGA in one pregnancy had an increased risk of one of these biologically related outcomes in a subsequent pregnancy. These findings could encourage enhanced surveillance for individuals who experience stillbirth, preterm birth, or SGA and desire a subsequent pregnancy.

Distinct patterns of comorbidity prior to diagnosis of incident systemic lupus erythematosus in the Danish population.

The objective of this study was to assess the cumulative prevalence of pre-existing comorbidities among patients diagnosed with systemic lupus erythematosus (SLE) in Denmark. The study included patients aged ≥18 years at the index date set to the date of first registration of SLE in the Danish National Patient Registry (DNPR) between 1996 and 2018. Up to 19 age- and sex-matched general population comparators per case were selected. Comorbidity diagnoses were retrieved from the DNPR based on International Classification of Diseases codes. We estimated cumulative prevalence of various comorbidities among cases and comparators, prevalence differences (PDs), and prevalence ratios (PRs), with PDs and PRs adjusted for age and sex, at the index date and 1, 2, 5, and 10 years before the index date. We identified 3,010 SLE cases and 57,046 comparators (mean age at index date: 47.3 years). Most comorbidities occurred more often in SLE patients versus comparators at the index date and up to 10 years before. Overrepresented comorbidities in SLE patients 10 years before SLE diagnosis included neuropsychiatric, cardiovascular, and venous thromboembolic diseases; PDs (95% CI) were 2.3% (1.4-3.3%), 1.3% (0.6-1.9%), and 1.1% (0.6-1.5%), respectively; corresponding PRs (95% CI) were 1.5 (1.3-1.8), 1.7 (1.4-2.1), and 4.3 (3.1-6.1). We found a higher prevalence of multiple comorbidities-not only at the time of SLE diagnosis but likewise during the 10-year pre-diagnosis period-among individuals with SLE. These findings underscore the importance of early clinical vigilance toward comorbidities starting in the diagnostic phase of SLE.

Systemic lupus erythematosus during pregnancy is not associated with school performance in offspring - A Danish population-based study.

INTRODUCTION: Systemic lupus erythematosus (SLE) in pregnancy is considered a risk factor for a range of adverse outcomes in the offspring. Studies have indicated increased risk of neurodevelopmental disorders such as autism spectrum disorders, dyslexia and ADHD. However, the overall long-term cognitive development of children born to women with SLE has scarcely been examined. In this study, we compare test scores from the Danish National School Tests of children born to women SLE with children of the background population. METHODS: We included all singleton children born in Denmark between 1995 and 2008, who were listed in the Danish National School Test Register (n=738,862). Children born to women with SLE were identified through linkage of national healthcare registers. We assessed the children's performance in the national school tests between 2nd and 8th grade, in reading and mathematics. Information on the mothers' redeemed prescriptions in pregnancy was included in stratified analyses. Differences of mean test scores were derived from linear regressions and compared according to maternal SLE status, and predefined categories of medication exposures. RESULTS: In total, 312 (0.04%) children were born to mothers with SLE. There were no differences in performance in neither reading nor mathematics tests between those born to mothers with SLE and children born to mothers without SLE. When stratifying on medication exposures among children whose mothers had SLE, there was a non-significant tendency towards poorer results among those exposed to hydroxychloroquine and/or immunosuppressants (n=31), compared to those not exposed to these medications. A similar tendency was not observed among children whose mothers received hydroxychloroquine for non-SLE reasons (n=1,235). CONCLUSION: This study indicates no major harmful effect on the child's neurocognitive development from exposure in utero to SLE, hydroxychloroquine and/or immunosuppressants, as measured by school performance.

Evidence of under-reporting of early-onset preeclampsia using register data.

BACKGROUND: Early-onset preeclampsia, traditionally defined as presenting before 34 gestational weeks, is associated with even higher risks of perinatal death, placental abruption, and stroke, than late-onset preeclampsia. OBJECTIVE: We estimated the degree of misclassification in a high-risk population of lupus pregnancies and a general population comparator when gestational age at delivery defined preeclampsia phenotype compared to first preeclampsia diagnosis. METHODS: Patients with lupus and general population comparators from Sweden with ≥1 singleton pregnancy in the Medical Birth Register with a documented ICD code for preeclampsia were included (2002-2016). We used gestational age at delivery (<34 versus ≥34 weeks) to phenotype preeclampsia early- versus late-onset and then reclassified based on first preeclampsia diagnosis date in the Patient Register. We cross-tabulated the two definitions and calculated sensitivity using the visit-based definition as the reference standard for general population and lupus pregnancies, overall and among nulliparous women. RESULTS: 331 pregnancies were diagnosed with preeclampsia, of which 322 were in both registers. Of those, 58 were early-onset based on gestational age at delivery (n = 29 in lupus pregnancies). Overall, 9% of early-onset preeclampsia in lupus (sensitivity 91%, 95% confidence interval [CI] 75, 98) was misclassified as late-onset compared to 19% in the general population (sensitivity 81%, 95% CI 64, 92). We noted similar misclassification (4% vs 22%) among nulliparous women. CONCLUSIONS: In the general population, early-onset preeclampsia was more likely misclassified as late-onset than in the high-risk lupus population. Relying on gestational age at delivery to phenotype preeclampsia, this way underestimates the occurrence of early-onset preeclampsia. This also suggests that the burden of early-onset preeclampsia as a public health concern may be under-reported, although this may be more applicable to milder preeclampsia where expectant management is employed. Research of biological and maternal predictors of early-onset preeclampsia may be dealing with differentially misclassified outcomes or samples.

Does Hydroxychloroquine Protect against Preeclampsia and Preterm Delivery in Systemic Lupus Erythematosus Pregnancies?

OBJECTIVE: Systemic lupus erythematosus (SLE) increases the risk of complications in pregnancy. Hydroxychloroquine (HCQ) decreases flares and neonatal lupus syndrome. Limited evidence suggests that HCQ also reduces preeclampsia and preterm birth in SLE pregnancies. We studied whether HCQ was associated with lower odds of preeclampsia and preterm delivery in SLE pregnancies. STUDY DESIGN: We conducted a retrospective cohort study of 129 deliveries of 110 patients with SLE delivered at a single institution (2000-2017). HCQ exposure and preeclampsia, along with other clinical data, were extracted from chart review. Crude and multivariable-adjusted logistic regression estimated odds ratios (ORs) and 95% confidence intervals (CIs). RESULTS: A total of 41% were exposed to HCQ, of whom 13.5% were complicated by preeclampsia versus 26.3% unexposed to HCQ (adjusted OR = 0.5; 95% CI: 0.2-1.4). The difference was pronounced for first pregnancies (7 vs. 44%), but power was limited. The difference in preterm deliveries was less pronounced comparing HCQ-exposed pregnancies with HCQ-unexposed pregnancies (34 vs. 40.8%; OR = 0.3; 95% CI: 0.3-1.5). CONCLUSION: Pregnant SLE patients trended toward less preeclampsia and preterm delivery when treated with HCQ. Future larger studies are needed to increase the statistical power, account for additional potential confounders, and more fully account for parity.

Preterm Delivery Phenotypes in Systemic Lupus Erythematosus Pregnancies.

OBJECTIVE: Women with systemic lupus erythematosus (SLE) are at a greater risk of preterm delivery, many of which may be medically indicated (iatrogenic). We investigated preterm delivery phenotypes in SLE and general population comparators and assessed the role of preeclampsia. STUDY DESIGN: We used population-based Swedish Register data (2001-2013) and defined maternal SLE as ≥2 SLE-coded discharge diagnoses from the Patient Register with ≥1 coded by an appropriate specialist. Women from the general population were identified using the Total Population Register. Preterm delivery was defined as <37 weeks and separated into spontaneous and iatrogenic, as well as later versus extremely preterm (32 to <37 weeks vs. <32 weeks). Maternal comorbidity was assessed, and the proportion mediated by preeclampsia was calculated examining first, subsequent, and all pregnancies. RESULTS: Preterm delivery was more common in SLE for the first (22 vs. 6%) and subsequent (15 vs. 4%) pregnancies among 781 SLE-exposed pregnancies and 11,271 non-SLE pregnancies. Of SLE-exposed first births, 27% delivered before 32 weeks, and 90% were iatrogenic (compared with 47% of non-SLE first births). CONCLUSION: Preterm delivery complicates a greater proportion of SLE pregnancies than general population pregnancies, and a considerable proportion of risk is mediated through preeclampsia.

The Representation of Gender and Race/Ethnic Groups in Randomized Clinical Trials of Individuals with Systemic Lupus Erythematosus.

PURPOSE OF REVIEW: This review evaluated gender and race/ethnic representation in randomized controlled trials (RCTs) of patients with systemic lupus erythematosus (SLE). RECENT FINDINGS: Whites comprise 33% of prevalent SLE cases and comprised 51% of RCT enrollees. Blacks encompass 43% of prevalent SLE cases, but only represented 14% of RCT enrollees. Hispanics comprise 16% of prevalent SLE cases and 21% of RCT enrollees, while Asians comprise 13% of prevalent SLE cases and 10% of RCT enrollees. Males encompass 9% of SLE cases and 7% of RCT enrollees. The reporting and representation of males have remained stable over time, although their representation in RCTs is slighter lower than the prevalence of SLE in males. The representation of Hispanics, Asians, and Native Americans increased over time. However, the representation of blacks among RCT participants has decreased since 2006-2011. RCTs among SLE patients need larger sample sizes in order to evaluate heterogeneity in outcomes among racial subgroups. It is imperative that novel strategies be developed to recruit racial minorities with SLE by identifying and improving barriers to RCT enrollment in order to better understand the disease's diverse population.

Stroke in systemic lupus erythematosus: a Swedish population-based cohort study.

OBJECTIVE: To study the occurrence of ischaemic and haemorrhagic stroke in systemic lupus erythematosus (SLE) compared with the general population by age, sex and time since SLE diagnosis METHODS: Adults with incident SLE were identified from the Swedish National Patient Register (NPR, n=3390) and general population comparators from the Total Population Register were matched on age, sex and county (n=16730). Individuals were followed prospectively until first of death, December 2013, emigration or incident stroke (identified from the NPR, Cause of Death Register and the Stroke Register). Incidence rates, rate differences and HR were estimated comparing SLE with non-SLE. Estimates were stratified by sex, age and time since diagnosis. RESULTS: We observed 126 strokes in SLE and 304 in the general population. Individuals with SLE had a twofold increased rate of ischaemic stroke compared with the general population (HR 2.2; 95% CI 1.7 to 2.8). The HR for intracerebral haemorrhage was 1.4 (95% CI 0.7 to 2.8). There was effect modification by sex and age, with the highest HRs for females and individuals <50 years old. The HR for ischaemic stroke was highest in the first year of follow-up (3.7; 95% CI 2.1 to 6.5). CONCLUSIONS: The relative risk of ischaemic stroke in SLE was more than doubled compared with the general population, and importantly, the highest relative risks were observed within the first year after SLE diagnosis. Thus, the first encounter with patients presents an opportunity for rheumatologists to screen for risk factors and intervene.

Medication use among pregnant women with systemic lupus erythematosus and general population comparators.

Objective: The aim was to characterize SLE medication trends before, during and after pregnancy and to compare other commonly used medications during SLE pregnancies with non-SLE pregnancies. Methods: Women with pregnancies ending in live birth or stillbirth were identified from the Swedish Medical Birth Register (2006-12). National registers were used to identify women with prevalent SLE during pregnancy and a sample without SLE and to identify prescription medications dispensed from 3 months pre-pregnancy until 6 months postpartum. We reported the prevalence of DMARDs, systemic CSs and NSAIDs (aspirin reported separately) in SLE pregnancies. We calculated prevalence estimates of other medications that were dispensed during pregnancy to ⩾ 5% of SLE pregnancies and for the same medications among non-SLE pregnancies. Results: There were 483 pregnancies among women with SLE and 5723 pregnancies among women without SLE. In SLE pregnancies, 49.3% had one or more dispensing for DMARDs during pregnancy; the prevalence was 48.0% for CSs, 40.8% for aspirin and 6.0% for other NSAIDs and varied by pregnancy period. The prevalence of common medications among SLE pregnancies was 1.2- to 20-fold higher than among non-SLE pregnancies; for example, dalteparin (20.9 vs 1.0%), paracetamol (18.2 vs 2.9%) and levothyroxine (15.9 vs 4.9%). Conclusion: In nearly half of SLE pregnancies, women were dispensed DMARDs and CSs. Commonly used medications in SLE pregnancies had far higher prevalence estimates compared with non-SLE pregnancies. Research regarding benefits and risks of commonly used medications on SLE pregnancies, breast milk and long-term outcomes for offspring is needed.

Cervical neoplasia in systemic lupus erythematosus: a nationwide study.

Objective: The aim was to examine the risk of cervical neoplasia in women with SLE, overall and with respect to treatment, compared with women from the general population. Methods: By linking national Swedish registers, we assembled a cohort including women with SLE (n = 4976) and matched general population comparators (n = 29 703). Two subcohorts of treated SLE patients were defined on the basis of treatment with antimalarials (n = 1942) and other immunosuppressants (AZA, CYC, ciclosporin, MTX, MMF or rituximab; n = 2175). The main outcome was defined as a first cervical neoplasia (dysplasia or cancer) during follow-up. Secondary outcomes were first cervical intraepithelial neoplasia (CIN) 1; first CIN grades 2-3; and first invasive cervical cancer during follow-up (2006-12). Cox regression models estimated relative risks adjusted for age, level of education, health-care utilization, number of children, marital status, family history of cervical cancer and prior cervical screening. Results: Based on 121 events of cervical neoplasia during 23 136 person-years among SLE patients, there was an increased risk of any cervical neoplasia compared with the general population [hazard ratio (HR) = 2.12 (95% CI: 1.65, 2.71)]. The risk of CIN 1 [HR = 2.33 (95% CI: 1.58, 3.44)], CIN 2-3 [HR = 1.95 (95% CI: 1.43, 2.65)], but not invasive cervical cancer [HR = 1.64 (95% CI: 0.54, 5.02)], was increased in women with SLE. The subcohort treated with other immunosuppressants was at highest risk of cervical neoplasia. Conclusion: SLE is a risk factor for cervical neoplasia, in particular for pre-malignant cervical lesions. Among patients with SLE, the risk is higher among those treated with immunosuppresants compared with those treated with antimalarials.

Early-onset Preeclampsia in Lupus Pregnancy.

BACKGROUND: Systemic lupus erythematosus (SLE) is a chronic systemic autoimmune disease that occurs during childbearing years and has been associated with preeclampsia. However, little is known about preeclampsia of early onset, which is associated with severe adverse maternal and perinatal outcomes. METHODS: Using national population-based Swedish registers we identified women with SLE (≥2 visits with corresponding ICD codes) and a sample without SLE who gave birth to singleton infants 2001-12. Risk ratios (RR) and 95% confidence intervals (CI) for early-onset preeclampsia (defined by ICD codes corresponding to preeclampsia registered at <34 weeks) in SLE women were calculated based on adjusted modified Poisson models for first, subsequent, and all pregnancies. RESULT: Among 742 births to women with SLE and 10 484 births to non-SLE women, there were 32 (4.3%) and 55 (0.5%) diagnoses of early-onset preeclampsia respectively. SLE was associated with an increased risk of early-onset preeclampsia (RR 7.8, 95% CI 4.8, 12.9, all pregnancies). The association remained similar upon restriction to women without pregestational hypertension. Adjustment for antiphospholipid syndrome (APS)-proxy attenuated the association. RRs for early-onset preeclampsia were smaller for subsequent pregnancies (RR 4.7, 95% CI 2.0, 11.2) compared to first and all (see above). CONCLUSION: Women with SLE are at increased risk of early-onset preeclampsia and this increased risk may be independent of the traditional risk factors such as pregestational hypertension, APS, BMI, or smoking. Women with SLE during pregnancy should be closely monitored for early-onset preeclampsia and future research needs to identify the non-traditional preeclampsia factors that might cause this serious outcome.

Predictors of work disability during the first 3 years after diagnosis in a national rheumatoid arthritis inception cohort.

OBJECTIVE: To identify predictors of sick leave and disability pension in patients with early rheumatoid arthritis (RA). METHODS: Individuals aged 19-59 years diagnosed with early RA (≤12 months symptom duration) were identified in the Swedish Rheumatology Quality Register (1999-2007; n=3029). We retrieved days of sick leave and disability pension from the Swedish Social Insurance Agency and baseline predictors of total work days lost during 3 years after RA diagnosis were investigated using linear regression. Due to effect modification by baseline work ability (defined as work days lost the month before diagnosis), analyses were stratified into three categories: full=0 work days lost the month before diagnosis; partial=1-29 work days lost; and none=30 work days lost. RESULTS: 71% of patients with full baseline work ability still had full work ability after 3 years compared with 36% (p<0.001) and 18% (p<0.001) of those with partial and no work ability at baseline, respectively. Elevated baseline levels of HAQ and DAS28, higher age, lower education level and unemployment were associated with more work days lost during 3 years in all strata of baseline work ability (all p<0.05). In a separate analysis, more objective variables (ESR, CRP and swollen joints) were not. Generally, the largest regression coefficients were seen for patients with partial baseline work ability. CONCLUSIONS: Work ability at RA diagnosis was the most important predictor of 3-year sick leave and disability pension. Taking this into account, HAQ, DAS28, age and education level were also significant predictors, whereas ESR and CRP were not.