3.2 Factors Associated with QTc Interval
Results showed significantly different QTc intervals between patients
with and without hypertension (423.7 ± 20.3 ms vs. 418.0 ± 16.8 ms, p =
0.011, respectively). No significant difference was observed between the
QTc intervals between patients with and without diabetes, or male and
female (Fig. 1). In addition, significantly longer QTc intervals were
observed in patients with higher disease activity scores as assessed by
SDAI, CDAI, DAS28-ESR, and DAS28-CRP (all p values <0.001,
compared by ANOVA, see Fig. 2).
In the univariate linear correlation analysis, age, heart rate, VAS
score, CDAI, SDAI, HAQ, DAS28-ESR, and DAS28-CRP were positively
associated with QTc interval (Table 2). A significant association was
identified between the QTc interval and ESR (p < 0.0001) and
CRP (p = 0.001). Differences in QTc interval were also observed between
patients with an ESR of ≥30 and <30 (418.1 ± 17.2 ms vs. 426.7
± 21.4 ms, p = 0.004), as shown in Fig. 1.
In the multivariate linear regression analysis, age, sex, HAQ, and CRP
levels were included in Model 1; SDAI and DAS28-ESR were included in
Models 2 and 3, respectively (Table.2). As a result, age, male sex, and
CDAI were independently associated with the QTc interval in Model 1. In
Model 2, age, male sex, and SDAI were independently associated with the
QTc interval, and an independent association was observed between the
DAS28-ESR and QTc interval in Model 3 (p = 0.0004).