2.3. Statistical analysis
All
statistical analyses were conducted with SPSS version 23.0 (SPSS Inc.,
Chicago, Illinois, USA) software. Numerical data were compared with an
independent sample t -test or the Mann–Whitney–Wilcoxon test.
Categorical data were compared with the Chi-square test or Fisher’s
exact test.
Spearman’s
nonparametric correlation test was applied to examine the associations
between serum C1q levels and Kerr’s score/ESR/hs-CRP. We selected the
cutoff values for serum C1q, ESR, hs-CRP and the combination of three
indicators (C1q, ESR and hs-CRP) using receiver operating characteristic
(ROC) curves with MedCalc software (v.15.2) to compare the accuracies of
these markers with disease activity identification. The cutoff points of
these markers were the values with the highest Youden’s Index
(sensitivity+specificity-1) score. A p -value less than 0.05 was
considered to be statistically significant.
3.
RESULTS
Of the 190 TA patients, 178were female, and 47patients had active
disease based on the NIH criteria (Table 1). In addition, 29 of the TA
patients in our study were naïve to corticosteroid or immunosuppressant
treatment. Malaise (71.1%), headache (47.9%) and chest distress
(27.4%) were the three most common constitutional
symptoms,
and Numano subtype V was common among the TA
patients.
The prevalence of claudication differed between the TA patients with
active and stable disease
(p =0.018).
Four of the patients with active disease had Numano subtype IIa, whereas
no Numano IIa cases were in clinical remission (p =0.003),
Furthermore, the prevalence of hypertension was notable between
untreated TA patients and treated patients (p =0.003).
Compared
with the healthy controls, patients with TA had higher ESR and C1q
levels (Table 1, Figure 1). However, the level of hs-CRP was similar
between the TA patients and healthy controls. Compared with patients who
had inactive disease, those with active disease had higher levels of
serum
C1q
and hs-CRP as well as ESR (Table 1, Figure 1). Similarly,
treatment-naïve
patients had higher
serumC1q,
ESR and hs-CRP than those who had always been
treated
with corticosteroids or at least one immunosuppressant (Table 1, Figure
1). We further analyzed the relationship between serum C1qand
Kerr’s
score/ESR/hs-CRP with the Spearman correlation test and found that in
our TA patients, serum C1q levels correlated significantly with Kerr’s
score, ESR and hs-CRP (Table 2).
The
areas under the ROC curve (AUCs) for C1q, ESR and hs-CRP were 0.752,
0.825, and 0.834, respectively, though without significant differences
(Table 3, Figure 2). Nevertheless, when the three indicators (C1q, ESR
and hs-CRP) were combined, the AUC increased to 0.845. At the same time,
the AUCs between the combination of the three indicators (C1q, ESR and
hs-CRP) and hs-CRP with C1q were significantly different from each
other. A serum cutoff value of 167.15 mg/L C1q maximized the disease
activity assessment capacity, with a sensitivity/specificity of
77.80%/64.90%. Using the established
ESR
and hs-CRP thresholds of our center, ESR and hs-CRP were able to
identify disease activity with a sensitivity/specificity of
80.00%/81.70% and 70.20%/86.50%, respectively, and the sensitivity
increased to 85.10% when the three indicators (C1q, ESR and hs-CRP)
were combined (Table 3, Figure 2).