ABSTRACT
Since the era of evidence-based medicine, it has become a matter of course to use statistics to create objective evidence in clinical research. As an extension of this, it has become essential in clinical research to calculate the correct sample size to demonstrate a clinically significant difference before starting the study.Also, because sample size calculation methods vary from study design to study design, there is no formula for sample size calculation that applies to all designs. It is very important for us to understand this. In this review, each sample size calculation method suitable for various study designs was introduced using the R program (R Foundation for Statistical Computing). In order for clinical researchers to directly utilize it according to future research, we presented practice codes, output results, and interpretation of results for each situation.
ABSTRACT
Objective@#To elucidate whether clinical features and the weighted genetic risk score (wGRS) were associated with the presence of lupus nephritis (LN). @*Methods@#We retrospectively divided patients with systemic lupus erythematosus (SLE, n=1,078) into biopsy-proven LN (n=507) and non-LN groups (non-LN, n=571). Baseline clinical features, serologic markers, and the wGRS were collected. The wGRS was calculated from 112 non-human leukocyte antigen (non-HLA) loci and HLA-DRβ1 amino acid haplotypes for SLE. Associations among clinical features, wGRS, and the presence of LN were identified. @*Results@#In the multivariate analysis, patients with LN were younger at diagnosis (odds ratio [OR]=0.97, p＜0.001), had more pleuritis (OR=2.44, p＜0.001) and pericarditis (OR=1.62, p=0.029), had a higher detection rate of anti-double stranded deoxyribonucleic acid (anti-dsDNA antibodies, OR=2.22, p＜0.001), anti-Smith antibodies (anti-Sm antibodies, OR=1.70, p=0.002), low level of complement (OR=1.37, p=0.043) and absence of antiphospholipid antibodies (aPL antibodies, OR=1.60, p=0.002), and had higher wGRS (OR=1.16, p=0.012). Mediation analysis suggested that anti-Sm antibodies and low complement could be mediators in the relationship between high wGRS and the presence of LN. @*Conclusion@#Onset age, pleuritis, pericarditis, several serologic markers, and wGRS were associated with the presence of LN. Anti-Sm antibodies and low complement appeared to mediate the indirect relationship between wGRS and the presence of LN.
ABSTRACT
Objective@#To elucidate whether clinical features and the weighted genetic risk score (wGRS) were associated with the presence of lupus nephritis (LN). @*Methods@#We retrospectively divided patients with systemic lupus erythematosus (SLE, n=1,078) into biopsy-proven LN (n=507) and non-LN groups (non-LN, n=571). Baseline clinical features, serologic markers, and the wGRS were collected. The wGRS was calculated from 112 non-human leukocyte antigen (non-HLA) loci and HLA-DRβ1 amino acid haplotypes for SLE. Associations among clinical features, wGRS, and the presence of LN were identified. @*Results@#In the multivariate analysis, patients with LN were younger at diagnosis (odds ratio [OR]=0.97, p＜0.001), had more pleuritis (OR=2.44, p＜0.001) and pericarditis (OR=1.62, p=0.029), had a higher detection rate of anti-double stranded deoxyribonucleic acid (anti-dsDNA antibodies, OR=2.22, p＜0.001), anti-Smith antibodies (anti-Sm antibodies, OR=1.70, p=0.002), low level of complement (OR=1.37, p=0.043) and absence of antiphospholipid antibodies (aPL antibodies, OR=1.60, p=0.002), and had higher wGRS (OR=1.16, p=0.012). Mediation analysis suggested that anti-Sm antibodies and low complement could be mediators in the relationship between high wGRS and the presence of LN. @*Conclusion@#Onset age, pleuritis, pericarditis, several serologic markers, and wGRS were associated with the presence of LN. Anti-Sm antibodies and low complement appeared to mediate the indirect relationship between wGRS and the presence of LN.