Blood immunophenotyping identifies distinct kidney histopathology and outcomes in patients with lupus nephritis.

Lupus nephritis (LN) is a frequent manifestation of systemic lupus erythematosus, and fewer than half of patients achieve complete renal response with standard immunosuppressants. Identifying non-invasive, blood-based pathologic immune alterations associated with renal injury could aid therapeutic decisions. Here, we used mass cytometry immunophenotyping of peripheral blood mononuclear cells in 145 patients with biopsy-proven LN and 40 healthy controls to evaluate the heterogeneity of immune activation in patients with LN and to identify correlates of renal parameters and treatment response. Unbiased analysis identified 3 immunologically distinct groups of patients with LN that were associated with different patterns of histopathology, renal cell infiltrates, urine proteomic profiles, and treatment response at one year. Patients with enriched circulating granzyme B+ T cells at baseline showed more severe disease and increased numbers of activated CD8 T cells in the kidney, yet they had the highest likelihood of treatment response. A second group characterized primarily by a high type I interferon signature had a lower likelihood of response to therapy, while a third group appeared immunologically inactive by immunophenotyping at enrollment but with chronic renal injuries. Main immune profiles could be distilled down to 5 simple cytometric parameters that recapitulate several of the associations, highlighting the potential for blood immune profiling to translate to clinically useful non-invasive metrics to assess immune-mediated disease in LN.

A Randomized, Placebo-Controlled Phase III Extension Trial of the Long-Term Safety and Tolerability of Anifrolumab in Active Systemic Lupus Erythematosus.

OBJECTIVE: To explore long-term safety and tolerability of anifrolumab 300 mg compared with placebo in patients with systemic lupus erythematosus (SLE) who completed a Treatment of Uncontrolled Lupus via the Interferon Pathway (TULIP) trial and enrolled in the placebo-controlled 3-year long-term extension (LTE) study (ClinicalTrials.gov identifier: NCT02794285). METHODS: In the blinded LTE study, patients continued anifrolumab 300 mg, switched from anifrolumab 150 mg to 300 mg, or were re-randomized from placebo to receive either anifrolumab 300 mg or to continue placebo, administered every 4 weeks. Primary comparisons in the LTE study were between patients who received anifrolumab 300 mg or placebo throughout the TULIP and LTE studies. For rare safety events, comparisons included patients who received any anifrolumab dose during TULIP or LTE. When exposure differed, exposure-adjusted incidence rates (EAIRs) per 100 patient-years were calculated. RESULTS: In the LTE study, EAIRs of serious adverse events (SAEs) were 8.5 with anifrolumab compared with 11.2 with placebo; likewise, EAIRs of AEs leading to treatment discontinuation were 2.5 versus 3.2, respectively. EAIRs of non-opportunistic serious infections were comparable between groups (3.7 with anifrolumab versus 3.6 with placebo). Exposure-adjusted event rates of COVID-related AEs, including asymptomatic infections, were 15.5 with anifrolumab compared with 9.8 with placebo. No COVID-related AEs occurred in fully vaccinated individuals. EAIRs of malignancy and major acute cardiovascular events were low and comparable between groups. Anifrolumab was associated with lower cumulative glucocorticoid use and greater mean improvement in the SLE Disease Activity Index 2000, compared with placebo. CONCLUSION: This LTE study represents the longest placebo-controlled clinical trial performed in SLE to date. No new safety findings were identified in the LTE study, supporting the favorable benefit-risk profile of anifrolumab for patients with moderate-to-severe SLE receiving standard therapy.

Is It Time to Bring Back Knee Washout?

Washout of knee joint contents, whether by arthrotomy, arthroscopy, or percutaneous methods, can remove phlogistic material contributing to the problem at hand. Observations dating from the turn of the last century coupled with multiple trials suggest such that an intervention can be useful in the management of osteoarthritis, inflammatory arthropathies, crystal arthritis, and septic arthritis. We suggest that this intervention-applicable at the bedside with minimal cost, preparation, or expertise-be reconsidered as an adjunct in management of these disorders.

Regarding Arthroscopy: Can Orthopedists and Rheumatologists Be Friends?

BACKGROUND/OBJECTIVE: Rheumatologists' interest in arthroscopy began before the 1980s, when many era practitioners began to take up the procedure in earnest. Some of the important players in pre-World War II explorations of arthroscopy were rheumatologists, and the father of modern arthroscopy Makei Watanabe counted many rheumatologists among his postwar students, who were publishing about arthroscopic insights into rheumatic conditions in the 1960s and 1970s. We chose to review this evolution to demonstrate the diverging interests of rheumatologists and orthopedists in arthroscopy and emphasize the chances for reconciliation and cooperation. Methods involve our personal recollection and review of the literature. RESULTS: Guidelines for the practice of arthroscopy were published by the American Rheumatism Association (now the American College of Rheumatology) 7 years before similar guidelines appeared from the Arthroscopy Association of North America. American rheumatologists ceased arthroscopy when controlled trials showed no effect in osteoarthritis beyond placebo and biologics for synovitis virtually eliminated situations in which synovectomy might be considered. The research potential of arthroscopy has been realized mainly by European rheumatologists, although the ultrasound-guided biopsy is supplanting arthroscopy as means to secure synovium for investigation, despite the advantages of the latter, such as the ability to obtain larger amounts of tissue, select tissue based on macroscopic appearance, sample multiple area in the same joint, and deliver the potentially therapeutic effect of washout. New miniscopes suitable for office use could restore some of the lagging interest in arthroscopy for investigation. Orthopedists have generally been resistant to rheumatologists doing arthroscopy but would not be sharing any turf with rheumatologists using the miniscope. CONCLUSIONS: We hope that we orthopedists and rheumatologists could be friends as we enter this new phase of arthroscopy as we use the technique for different purposes.

Will rheumatologists ever pick up the arthroscope again?

Conditions prompting physicians and surgeons first adapting endoscopes to peer into joints were mainly the sort of synovial conditions that would concern today's rheumatologists. Rheumatologists were among the pre-World War II pioneers developing and documenting arthroscopy. The post-War father of modern arthroscopy, Watanabe, found rheumatologists among his early students, who took back the technique to their home countries, teaching orthopedists and rheumatologists alike. Rheumatologists described and analyzed the intra-articular features of their common diseases in the '60s and '70s. A groundswell of interest from academic rheumatologists in adapting arthroscopy grew considerably in the '90s with development of "needle scopes" that could be used in an office setting. Rheumatologists helped conduct the very trials the findings of which reduced demand for their arthroscopic services by questioning the efficacy of arthroscopic debridement in osteoarthritis (OA) and also developing biological compounds that greatly reduced the call for any resective intervention in inflammatory arthropathies. The arthroscope has proven an excellent tool for viewing and sampling synovium and continues to serve this purpose at several international research centers. While cartilage is now imaged mainly by magnetic resonance imaging, some OA features - such as a high prevalence of visible calcinosis - beg further arthroscopy-directed investigation. A new generation of "needle scopes" with far superior optics awaits future investigators, should they develop interest.

Cancer Risk in a Large Inception Systemic Lupus Erythematosus Cohort: Effects of Demographic Characteristics, Smoking, and Medications.

OBJECTIVE: To assess cancer risk factors in incident systemic lupus erythematosus (SLE). METHODS: Clinical variables and cancer outcomes were assessed annually among incident SLE patients. Multivariate hazard regression models (overall risk and most common cancers) included demographic characteristics and time-dependent medications (corticosteroids, antimalarial drugs, immunosuppressants), smoking, and the adjusted mean Systemic Lupus Erythematosus Disease Activity Index 2000 score. RESULTS: Among 1,668 patients (average 9 years follow-up), 65 cancers occurred: 15 breast, 10 nonmelanoma skin, 7 lung, 6 hematologic, 6 prostate, 5 melanoma, 3 cervical, 3 renal, 2 each gastric, head and neck, and thyroid, and 1 each rectal, sarcoma, thymoma, and uterine cancers. Half of the cancers (including all lung cancers) occurred in past/current smokers, versus one-third of patients without cancer. Multivariate analyses indicated that overall cancer risk was related primarily to male sex and older age at SLE diagnosis. In addition, smoking was associated with lung cancer. For breast cancer risk, age was positively associated and antimalarial drugs were negatively associated. Antimalarial drugs and higher disease activity were also negatively associated with nonmelanoma skin cancer risk, whereas age and cyclophosphamide were positively associated. Disease activity was associated positively with hematologic and negatively with nonmelanoma skin cancer risk. CONCLUSION: Smoking is a key modifiable risk factor, especially for lung cancer, in SLE. Immunosuppressive medications were not clearly associated with higher risk except for cyclophosphamide and nonmelanoma skin cancer. Antimalarials were negatively associated with breast cancer and nonmelanoma skin cancer risk. SLE activity was associated positively with hematologic cancer and negatively with nonmelanoma skin cancer. Since the absolute number of cancers was small, additional follow-up will help consolidate these findings.

Arthroscopy in rheumatology: where have we been? Where might we go?

The aim of our manuscript is to illustrate the past, present and future role of rheumatologists performing arthroscopy. Doctors first began adapting endoscopes to inspect joints to assess synovial conditions that concern rheumatologists. Rheumatologists were among the pioneers developing arthroscopy. Students of the father of modern arthroscopy, Watanabe, included rheumatologists, who taught others once home. Rheumatologists assessed the intra-articular features of their common diseases in the 60s and 70s. Improvements in instrumentation and efforts by a few orthopaedists adapted a number of common joint surgical procedures for arthroscopy. Interest from rheumatologists in arthroscopy grew in the 90s with 'needle scopes' used in an office setting. Rheumatologists conducting the first prospective questioning arthroscopic debridement in OA and developing biological compounds reduced the call for arthroscopic interventions. The arthroscope has proven an excellent tool for viewing and sampling synovium, which continues to at several international centres. Some OA features-such as calcinosis-beg further arthroscopic investigation. A new generation of 'needle scopes' with far superior optics awaits future investigators.

The immune cell landscape in kidneys of patients with lupus nephritis.

Lupus nephritis is a potentially fatal autoimmune disease for which the current treatment is ineffective and often toxic. To develop mechanistic hypotheses of disease, we analyzed kidney samples from patients with lupus nephritis and from healthy control subjects using single-cell RNA sequencing. Our analysis revealed 21 subsets of leukocytes active in disease, including multiple populations of myeloid cells, T cells, natural killer cells and B cells that demonstrated both pro-inflammatory responses and inflammation-resolving responses. We found evidence of local activation of B cells correlated with an age-associated B-cell signature and evidence of progressive stages of monocyte differentiation within the kidney. A clear interferon response was observed in most cells. Two chemokine receptors, CXCR4 and CX3CR1, were broadly expressed, implying a potentially central role in cell trafficking. Gene expression of immune cells in urine and kidney was highly correlated, which would suggest that urine might serve as a surrogate for kidney biopsies.

Phase III trial results with blisibimod, a selective inhibitor of B-cell activating factor, in subjects with systemic lupus erythematosus (SLE): results from a randomised, double-blind, placebo-controlled trial.

BACKGROUND: Targeted inhibitors of B-cell activating factor (BAFF) have been evaluated in phase III trials in over 4000 patients with systemic lupus erythematosus (SLE). Post hoc analyses of these studies identify greater treatment effect in patients entering with higher disease activity, greater corticosteroid doses, anti double-stranded DNA (dsDNA) and low complement C3 or C4. OBJECTIVES: To evaluate the efficacy and safety of blisibimod, a BAFF inhibitor, in a population of patients with SLE enriched for high disease activity. METHODS: 442 patients with SLE with antinuclear antibodies or anti-dsDNA and Safety of Estrogen in Lupus Erythematosus National Assessment - Systemic Lupus Erythematosus Disease Activity Index (SELENA-SLEDAI) score ≥10 on standard-of-care medications were randomised to receive weekly subcutaneous blisibimod (200 mg) or placebo. Corticosteroid taper was encouraged from week 8. The primary end point was the week 52 SLE Responder Index-6 (SRI-6). RESULTS: The SRI-6 primary end point was not met. There was a statistically significant steroid-sparing effect, and significantly more blisibimod-treated subjects achieved corticosteroid taper. Increased blisibimod treatment effect on SRI-6 was observed in subjects who achieved a concomitant decrease in corticosteroid dose from baseline. In subjects with baseline urinary protein:creatinine ratio (UPCR) ≥56.5 mg/mmol, significantly higher proportions of blisibimod subjects achieved >50% reduction in UPCR and/or UPCR <56.5 mg/mmol. Reductions in SLE autoantibodies and B cells, and increases in complement C3 and C4 were observed with blisibimod.Blisibimod was well-tolerated. The most common adverse events were upper respiratory tract infection, urinary tract infection, injection site erythema/reaction and diarrhoea. CONCLUSIONS: Although the SRI-6 end point was not met, blisibimod was associated with successful steroid reduction, decreased proteinuria and biomarker responses. TRIAL REGISTRATION NUMBER: NCT01395745.

Economic Evaluation of Lupus Nephritis in the Systemic Lupus International Collaborating Clinics Inception Cohort Using a Multistate Model Approach.

OBJECTIVE: Little is known about the long-term costs of lupus nephritis (LN). The costs were compared between patients with and without LN using multistate modeling. METHODS: Patients from 32 centers in 11 countries were enrolled in the Systemic Lupus International Collaborating Clinics inception cohort within 15 months of diagnosis and provided annual data on renal function, hospitalizations, medications, dialysis, and selected procedures. LN was diagnosed by renal biopsy or the American College of Rheumatology classification criteria. Renal function was assessed annually using the estimated glomerular filtration rate (GFR) or estimated proteinuria. A multistate model was used to predict 10-year cumulative costs by multiplying annual costs associated with each renal state by the expected state duration. RESULTS: A total of 1,545 patients participated; 89.3% were women, the mean ± age at diagnosis was 35.2 ± 13.4 years, 49% were white, and the mean followup duration was 6.3 ± 3.3 years. LN developed in 39.4% of these patients by the end of followup. Ten-year cumulative costs were greater in those with LN and an estimated glomerular filtration rate (GFR) <30 ml/minute ($310,579 2015 Canadian dollars versus $19,987 if no LN and estimated GFR >60 ml/minute) or with LN and estimated proteinuria >3 gm/day ($84,040 versus $20,499 if no LN and estimated proteinuria <0.25 gm/day). CONCLUSION: Patients with estimated GFR <30 ml/minute incurred 10-year costs 15-fold higher than those with normal estimated GFR. By estimating the expected duration in each renal state and incorporating associated annual costs, disease severity at presentation can be used to anticipate future health care costs. This is critical knowledge for cost-effectiveness evaluations of novel therapies.

Clinical trial parameters that influence outcomes in lupus trials that use the systemic lupus erythematosus responder index.

Objective: The SLE Responder Index (SRI) is a composite endpoint used in SLE trials. This investigation examined the clinical trial elements that drive response measured by the SRI. Methods: Analyses are based on data from two phase 3 trials (n = 2262) that evaluated the impact of an anti-B-cell activating factor antibody on disease activity using SRI-5 as the primary endpoint (ClinicalTrials.gov NCT01196091 and NCT01205438). Results: The SRI-5 response rate at week 52 for all patients was 32.8%. Non-response due to a lack of SLEDAI improvement, concomitant medication non-compliance or dropout was 31, 16.5 and 19.1%, respectively. Non-response due to deterioration in BILAG or Physician's Global Assessment after SLEDAI improvement, concomitant medication compliance and trial completion was 0.5%. Disease activity in three SLEDAI organ systems was highly prevalent at baseline: mucocutaneous, 90.6%; musculoskeletal, 82.9%; and immunologic, 71.6%. Disease activity in each of the other organ systems was <11% of patients. Four clinical manifestations were highly prevalent at baseline: arthritis, 82.6%; rash, 69.2%; alopecia, 58.2%; and mucosal ulcer, 32.5%. The combined prevalence of renal, vascular and CNS disease at baseline was 17.6%; these patients had high SRI-5 response rates. Adjustments to corticosteroids were allowed during the first 24 weeks. Increases in corticosteroids above 2.5 mg/day were observed in 16.2% of placebo patients over the first 24 weeks after randomization. Conclusion: The primary drivers of SRI-5 response were SLEDAI improvement, concomitant medication adherence and trial completion. Arthritis, rash, alopecia and mucosal ulcer were the most prevalent clinical manifestations at baseline. Corticosteroid increases and rare, highly weighted disease manifestations in SLEDAI can confound the SRI signal.

A Longitudinal Analysis of Outcomes of Lupus Nephritis in an International Inception Cohort Using a Multistate Model Approach.

OBJECTIVE: To study bidirectional change and predictors of change in estimated glomerular filtration rate (GFR) and proteinuria in lupus nephritis (LN) using a multistate modeling approach. METHODS: Patients in the Systemic Lupus International Collaborating Clinics inception cohort were classified annually into estimated GFR state 1 (>60 ml/minute), state 2 (30-60 ml/minute), or state 3 (<30 ml/minute) and estimated proteinuria state 1 (<0.25 gm/day), state 2 (0.25-3.0 gm/day), or state 3 (>3.0 gm/day), or end-stage renal disease (ESRD) or death. Using multistate modeling, relative transition rates between states indicated improvement and deterioration. RESULTS: Of 1,826 lupus patients, 700 (38.3%) developed LN. During a mean ± SD follow-up of 5.2 ± 3.5 years, the likelihood of improvement in estimated GFR and estimated proteinuria was greater than the likelihood of deterioration. After 5 years, 62% of patients initially in estimated GFR state 3 and 11% of patients initially in estimated proteinuria state 3 transitioned to ESRD. The probability of remaining in the initial states 1, 2, and 3 was 85%, 11%, and 3%, respectively, for estimated GFR and 62%, 29%, and 4%, respectively, for estimated proteinuria. Male sex predicted improvement in estimated GFR states; older age, race/ethnicity, higher estimated proteinuria state, and higher renal biopsy chronicity scores predicted deterioration. For estimated proteinuria, race/ethnicity, earlier calendar years, damage scores without renal variables, and higher renal biopsy chronicity scores predicted deterioration; male sex, presence of lupus anticoagulant, class V nephritis, and mycophenolic acid use predicted less improvement. CONCLUSION: In LN, the expected improvement or deterioration in renal outcomes can be estimated by multistate modeling and is preceded by identifiable risk factors. New therapeutic interventions for LN should meet or exceed these expectations.

Current advances in therapies for osteoarthritis.

PURPOSE OF REVIEW: Although osteoarthritis (OA) has received a paucity of attention from researchers in terms of drug development, there have been some significant findings relevant to clinical issues in OA that are summarized in this review. RECENT FINDINGS: Recent osteoarthritis research has focused on synovial, subchondral bone, and biomechanical effects of the disease. Results from a pilot study of patients treated with methotrexate demonstrated 20% pain reduction in 50% of patients and 40% pain reduction in 37% of patients. Data show that plasma levels of interleukin-1 receptor antagonist and synovial fluid levels of interleukin-6 and tumor necrosis factor-alpha associate with radiographic progression, suggesting that these mediators may be prognostic biomarkers and/or targets for drug development. Recent data suggest that subchondral bone features associate with structural progression, suggesting a need for therapeutic approaches that target this region. Patient-reported outcome measures and kinematic factors may predict success to an exercise treatment protocol and unloader braces appear to reduce the knee adduction moment, suggesting a need for a comprehensive review of the clinical effects of braces. SUMMARY: Advances in the understanding of key areas of osteoarthritis pathogenesis are helping define the spectrum of therapeutic targets that potentially should be explored to reduce the symptomatic and structural effects of osteoarthritis.

The modified Nail Psoriasis Severity Index: validation of an instrument to assess psoriatic nail involvement in patients with psoriatic arthritis.

OBJECTIVE: Patients with psoriasis and psoriatic arthritis (PsA) commonly have nail involvement. There is no validated psoriatic nail assessment tool. Recently, investigators developed the Nail Psoriasis Severity Index (NAPSI). Beginning with NAPSI, our goal was to validate a psoriatic nail assessment tool for use in clinical trials, and investigate correlations between nail and other PsA features. METHODS: Fingernails of 29 patients with PsA were photographed and scored. Clinical data were collected. Using the original NAPSI, analysis revealed high interrater variability of nail scores. Twenty patients' photographs were regraded using the modified NAPSI (mNAPSI). RESULTS: The mNAPSI scores had excellent interrater reliability (Cronbach's alpha 0.98). Nail scores and physicians' global nail severity visual analog scores showed good inter- and intrarater correlations (Spearman's rho 0.85 and 0.90-0.99, respectively; p < 0.01). Several clinical measures correlated with nail scores. CONCLUSION: The mNAPSI demonstrated excellent interrater reliability and construct validity, and may be a valuable tool.

Validation of American College of Rheumatology classification criteria for knee osteoarthritis using arthroscopically defined cartilage damage scores.

OBJECTIVE: To validate the ability of the American College of Rheumatology (ACR) clinical classification criteria and the ACR clinical plus radiographic classification criteria for osteoarthritis of the knee to predict articular cartilage damage. METHODS: Ninety subjects with knee osteoarthritis (OA) who were enrolled in a prospective study determining the therapeutic efficacy of arthroscopic irrigation were characterized as to whether they fulfilled the ACR clinical classification criteria or the ACR clinical plus radiographic classification criteria. Ten rheumatoid arthritis (RA) patients were included as controls. Cartilage damage was defined using the ACR/Knee Arthroscopy Osteoarthritis Scale (ACR/KAOS) system, which is a validated outcome instrument for knee OA based on arthroscopic visualization. Mean values of the damage scores in each group were calculated and compared by t-test to determine statistical significance between the 3 groups. RESULTS: The mean ACR/KAOS score for the 10 RA patients was 1.8 [SD 1.22; range 0 to 4]. Of the 90 OA patients who underwent arthroscopy, only 73 patients had sufficient videotape to make an accurate assessment by the blinded assessor. The mean ACR/KAOS score for the 6 OA patients who fulfilled only the ACR clinical classification was 17.4 [SD 11.3; range 5 to 34.3] and the mean ACR/KAOS score for the 67 patients who fulfilled the ACR clinical plus radiographic classification criteria was 42.0 [SD 29.1; range 5.1 to 118.4]. These differences were statistically significant (RA versus OA clinical P=0.02; RA versus OA clinical+radiographic P

Treatment of systemic lupus erythematosus by inhibition of T cell costimulation with anti-CD154: a randomized, double-blind, placebo-controlled trial.

OBJECTIVE: To evaluate the safety and efficacy of a humanized monoclonal antibody against CD154 (IDEC-131) in patients with active systemic lupus erythematosus (SLE). METHODS: In this phase II, double-blind, placebo-controlled, multiple-center, multiple-dose study, 85 patients with mild-to-moderately active SLE were randomized to receive 6 infusions of IDEC-131, ranging from 2.5 mg/kg to 10.0 mg/kg, or placebo over 16 weeks. Efficacy was assessed at week 20, primarily by the Systemic Lupus Erythematosus Disease Activity Index (SLEDAI) and secondarily, by multiple measures of disease activity. Safety was assessed through week 28 by clinical and laboratory evaluation. Immunogenicity studies were also performed. RESULTS: SLEDAI scores improved from the baseline levels of disease activity in all groups, including the placebo group. However, these scores were not statistically different among the IDEC-131 treatment and placebo groups at week 20. Evaluations of secondary variables did not indicate significant differences between the IDEC-131 treatment and placebo groups. The type and frequency of adverse events were similar between the IDEC-131 and placebo groups. CONCLUSION: IDEC-131 administered at doses ranging 2.5-10.0 mg/kg over 16 weeks was safe and well tolerated in patients with SLE. Efficacy of the drug compared with placebo was not demonstrated. There were statistically significant improvements from baseline in all groups, including the placebo group.

Familiality and co-occurrence of clinical features of systemic lupus erythematosus.

OBJECTIVE: To evaluate familiality of 15 clinical and laboratory features in systemic lupus erythematosus (SLE)-affected sibpairs, and to estimate correlations with the age at SLE diagnosis in affected sibpairs and parent-offspring pairs. METHODS: Concordance rates and sibling risk ratios were used as indicators of familiality for 15 manifestations of SLE. Pearson's correlations and paired t-tests were used to compare the age at SLE diagnosis in affected sibpairs and in parent-offspring pairs. RESULTS: Increased sibling risk ratios (1.9-3.9) for thrombocytopenia, discoid rash, neurologic disorder (defined as seizure or psychosis), and hemolytic anemia were observed in 159 SLE-affected sibpairs. Among these clinical features, paired expression of hemolytic anemia plus thrombocytopenia and hemolytic anemia plus neurologic disorder appeared to be more frequent in 709 SLE patients than would be expected by chance (P < 0.00001 and P < 0.007, respectively). The ratio of the presence of both hemolytic anemia and neurologic disorder was approximately 13 times higher in the younger affected sib than in the older affected sib (P < 0.02). Familiality of patient age at SLE diagnosis, as observed by relative correlations, was greater in 125 affected sibpairs (r = 0.67, P < 0.0001) than in 37 affected parent-offspring pairs (r = 0.47, P = 0.003). The median +/- SD age at SLE diagnosis was significantly lower in offspring (21.5 +/- 10.1 years) than in their parents (41.6 +/- 15.8 years) (P < 0.0001) but was not different in sibpairs. The combined non-Caucasian sibpairs had a younger mean age at SLE diagnosis compared with Caucasian sibpairs (P = 0.014). CONCLUSION: Evidence for familiality of thrombocytopenia, discoid rash, neurologic disorder, hemolytic anemia, and co-occurring neurologic disorder plus hemolytic anemia in SLE was observed in 159 affected sibpairs. Familiality of the age at SLE diagnosis in relative pairs suggests that shared genes and/or shared environmental exposures impact disease susceptibility. Shared immediate environmental triggers appear less compelling, because the average time between dates of diagnosis was 11 years in parent-offspring pairs and 7.5 years in affected sibpairs. The significantly earlier age at disease diagnosis in offspring compared with their parents suggests that some forms of anticipation might play a role in susceptibility to SLE. Stratifying families by subphenotypes that are familial may reduce heterogeneity and facilitate identification of genetic risk factors for SLE.