Department of Epidemiology and Biostatistics, University of South Carolina, Columbia, South Carolina, USA.
School of Dentistry, University of Maryland, Baltimore, Maryland, USA.
J Periodontol. 2021 Jul;92(7):975-982. doi: 10.1002/JPER.20-0376. Epub 2020 Nov 5.
Survival average causal effect (SACE) can give valid estimates of the periodontal treatment effect on birth outcomes in randomized controlled trials when fetal losses are unequal across the treatment arms. A regression-based method to estimate SACE using ordinary least squares (OLS) regression can be biased if the treatment effect varies across the outcome distribution. In this case quantile regression may be a suitable alternative.
We compared OLS and quantile regression models estimating SACE to calculate the effect of periodontal treatment on birthweight and gestational age in secondary analyses of publicly available Obstetrics and Periodontal Therapy (OPT) trial data.
Periodontal treatment tended to increase birthweight and gestational age at the lowest quantiles, remained flat in the middle quantiles, and trended to decrease both birthweight and gestational age in the highest quantiles. In quantile regression models estimating SACE the β-coefficients: 95% confidence intervals (CI) for the 5th, 50th, and 95th percentiles were 277.5: -141.0 to 696.0 g, 1.4: -107 to 110.3 g, and -84: -344 to 175.3 g for birthweight, and 0.6: -1.0 to 2.2 weeks, -0.1: -0.5 to 0.2 weeks, and -0.6: -1.0 to -0.1 weeks for gestational age. Estimates from OLS models estimating SACE were close to the null, β: 95% CI -4.7: 132.3 to 123.0 g for birthweight, and 0.03: -0.72 to 0.78 weeks for gestational age.
OLS models to evaluate SACE for periodontal treatment effects on birthweight and gestational age may be biased towards the null. Quantile regression may be a preferable alternative.
在随机对照试验中，如果治疗组之间的胎儿损失不均等，生存平均因果效应（SACE）可以对牙周治疗对出生结局的影响给出有效的估计。当治疗效果随结果分布而变化时，使用普通最小二乘法（OLS）回归估计 SACE 的回归方法可能存在偏差。在这种情况下，分位数回归可能是一种合适的替代方法。
我们比较了 OLS 和分位数回归模型来估计 SACE，以计算牙周治疗对出生体重和胎龄的影响，这是对公开可得的产科和牙周治疗（OPT）试验数据的二次分析。
牙周治疗在最低分位数时倾向于增加出生体重和胎龄，在中分位数时保持平稳，在最高分位数时倾向于降低出生体重和胎龄。在估计 SACE 的分位数回归模型中，β系数：第 5、50 和 95 个百分位的 95%置信区间（CI）分别为 277.5：-141.0 至 696.0 g、1.4：-107 至 110.3 g 和-84：-344 至 175.3 g 用于出生体重，0.6：-1.0 至 2.2 周，-0.1：-0.5 至 0.2 周，-0.6：-1.0 至-0.1 周用于胎龄。OLS 模型估计 SACE 的估计值接近零，β：95%CI-4.7：132.3 至 123.0 g 用于出生体重，β：0.03：-0.72 至 0.78 周用于胎龄。
评估牙周治疗对出生体重和胎龄影响的 SACE 的 OLS 模型可能存在偏差。分位数回归可能是一种更好的选择。
