Timing of Childhood-Onset Systemic Lupus Erythematosus Diagnosis Relative to Menarche and the Impact on Final Adult Height

Causal associations of birth body size and adult body size with systemic lupus erythematosus: a bidirectional mendelian randomization study

Objective

Body size is associated with the onset of systemic lupus erythematosus (SLE). However, the evidence for this association is inconclusive. In this study, we aimed to investigate the causal relationship between body size and SLE.

Method

We performed a bidirectional Mendelian randomization (MR) analysis that utilized summary statistics sourced from genome-wide association study (GWAS) data obtained from the IEU Open GWAS project website. The inverse variance weighting (IVW) method was used to evaluate the causality, and four additional MR methods were used to supplement the IVW results. Sensitivity analyses were performed using the Cochran's Q test, MR-Egger regression, leave-one-out analysis, and the Mendelian Randomization Pleiotropy RESidual Sum and Outlier (MR-PRESSO) global test.

Results

In the forward direction analysis, the IVW model demonstrated that birth weight (odds ratio (OR), 1.811; 95% confidence interval (CI), 1.174-2.793; p < 0.05) and adult height (OR, 1.225; 95% CI, 1.046-1.434; p < 0.05) were positively associated with SLE. Four additional MR scans were performed parallel to the IVW results. Conversely, SLE was a weak causal factor for increased height (OR, 1.010; 95% CI, 1.002-1.018; p < 0.05) using the IVW method. Heterogeneity, MR-Egger intercept, and leave-one-out analyses indicated that the results were robust. The MR-PRESSO suggested the presence of pleiotropy. Following the exclusion of instrumental variables (IVs) inducing pleiotropy, subsequent MR analysis yielded consistent results, thereby reinforcing the robustness of our findings.

Conclusion

Positive causal associations were observed between birth weight, adult height, and SLE incidence. In the reverse analysis, SLE was a weak causal factor for adult height.

Long-term growth and final adult height outcome in childhood-onset systemic lupus erythematosus

BACKGROUND

Growth impairment is the most common complication in patients with childhood-onset systemic lupus erythematosus (cSLE). There are limited data on risk factors affecting growth development in Asian patients with cSLE. This study aimed to determine the predictors of growth impairment in such patients.

METHODS

All SLE patients aged < 15 years diagnosed in Ramathibodi Hospital between 2006 and 2016 were enrolled in a retrospective cohort study. Baseline characteristics, including height, weight, clinical manifestations, disease activity score, and medications, were reviewed from medical records from the time at diagnosis to achievement of final adult height (FAH). Age at menarche in girls, adult voice appearance in boys, and parental height were collected by interview. Parent-adjusted FAH (PaFAH) Z-score was calculated as the difference between FAH Z-score for chronological age of the patients and their mid parental height-Z score. The patients were classified into two groups: (1) normal growth (PaFAH Z-score ≥ - 1.5, 2) growth impairment (PaFAH Z-score < - 1.5). Descriptive statistics and logistic regression analysis were used to analyze the data.

RESULTS

Of 106 cSLE patients, 19 (18%) were male and 87 (82%) were female. The mean age at study enrollment was 20.6 ± 3.0 years, mean age at diagnosis 12.1 ± 2.3 years, and mean age at achievement of FAH 17.5 ± 1.9 years. Growth impairment was found in 23.6% of patients (52.6% in boys and 17.2% in girls). Predictors of growth impairment were male sex, duration of disease before menarche in girls and adult voice appearance in boys, and cumulative corticosteroid dose (prednisolone equivalent) ≥230 mg/kg received before the late phase of puberty, with odds ratios of 7.07 (95%CI 2.11-23.74), 1.26 (95% CI 1.02-1.56), and 6.99 (95%CI 1.63-30.02), respectively.

CONCLUSIONS

One-fourth of cSLE patients developed growth impairment, which mostly affected male patients. Longer duration of disease before the late phase of puberty and corticosteroid dose ≥230 mg/kg received before the late phase of puberty were factors predictive of growth impairment.