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Table 2 Predictivity of complement in SLE flares

From: Predictive biological markers of systemic lupus erythematosus flares: a systematic literature review

Complement fraction(s) Number of patients (n) Findings Study
Positive results
 C3, C4 and CH50 57 Increased incidence of exacerbation in patients with decreased level of C3 or CH50 Tomioka et al., 2008 [7]
 C3 and C4 562 Low C3 level (< 900 mg/L) was an independent predictor of a severe SFI flare Petri et al., 2013 [9]
 C3 and C4 299 Low C3 and C4 were risk factors for a later A or B flare in the mucocutaneous, renal and haematologic systems Petri et al., 2009 [10]
 C3 32 Low baseline serum C3 (< 900 mg/L) was a predictor for shorter time to flare Ng et al., 2007 [36]
 C3 and C4 46 Baseline C4 titres were low (< 10 mg/dl) in a significantly higher percentage of relapsing patients El Hachmi et al., 2003 [8]
 C3 and C4 145 C4 level (< 11 mg/dl) was a significant prognostic factor for renal flares Illei et al., 2002 [35]
 CH50 60 CH50 level was an independent predictor of lupus flares Viallard et al., 2001 [38]
 C1q, C3, C4, C5 and C9 143 Decrease of C4, followed by decreases of C1q and C3 levels (< 40% of normal values), started 25 to 20 weeks before renal involvement Swaak et al., 1986 [12]
 C3a, C5a, C3 and C4 40 C3a levels rose significantly (>200 ng/ml) 1–2 months prior to flare Hopkins et al., 1988 [32]
 C3 189 Persistently low C3 level was a predictor of nephritic renal flares Mok et al., 2004 [23]
 C1q, C3, C4 27 When patients were clinically active, mean values of C1q, C4 and CH50 were the lowest obtained for these markers Lloyd and Schur, 1981 [19]
 C3 and C4 71 Lower C4 levels (< 12 mg/dl), but not C3 levels, significantly predicted renal flares Birmingham et al., 2010 [37]
 C3 and C4 218 For renal flares: low C3 (0.5–0.74 g/L), sensitivity 34.8%, specificity 63.1%; low C4 (0.1–0.13 g/L), sensitivity 19.4%, specificity 79% To et al., 2011 [27]
 C3 and C4 218 For severe flares: low C3 (0.5–0.74 g/L), sensitivity 29.2%, specificity 63%, PPV 2.3%, NPV 96.7%; low C4 (0.1–0.13 g/L), sensitivity 19.2%, specificity 79%, PPV 2.8%, NPV 96.0% To et al., 2011 [28]
 C3, C4, CH50 and complement split products: Ba, Bb; C4d; SC5b-9 86 Most sensitive marker of flare: elevated C4d (> 8.5 mg/ml). Highest specificity and greatest predictive value for flare: elevated Bb (> 1.2 mg/ml) Buyon et al., 1992 [33]
Negative results
 C3, C4 and C1q 202 Fluctuations were poor predictors of exacerbations Esdaile et al., 1996 [20]
 C3 and C4 53 Decreasing complement levels did not precede changes in disease activity Ho et al., 2001 [34]
 CH50 120 No consistent association of complement titre with flares in the subsequent year Mirzayan et al., 2000 [6]
 C3, C4 and CH50 73 No difference between patients who flared and patients who did not Walz LeBlanc et al., 1994 [31]
  1. NPV negative predictive value, PPV positive predictive value, SFI SLE Flare Index, SLE systemic lupus erythematosus