Egelberg J
School of Dentistry, Loma Linda University, CA.
J Clin Periodontol. 1989 Feb;16(2):120-3. doi: 10.1111/j.1600-051x.1989.tb01624.x.
The purpose of this report was to evaluate the magnitude of the regression towards the mean (RTM) relative to the observed changes in probing measurements following periodontal therapy in 2 groups of patients. Regression lines were calculated for observed changes in probing depths and probing attachment levels related to the initial probing depths of the individual sites. Regression lines, adjusted for the RTM effect, were also calculated. For the extreme subgroups of recorded shallow and deep sites, the RTM effect (mm) was found to amount to a maximum of 0.6 mm. It appears unlikely that erroneous conclusions have been made in previous clinical studies evaluating probing depth changes in deep sites, since the RTM accounts for a limited portion of the observed changes. For probing depth changes in shallow sites and for probing attachment level changes in both shallow and deep sites, the RTM accounts for a larger proportion of the observed mm changes. It therefore seems prudent to be careful about interpretation of these changes in clinical studies, where the RTM effect has not been adjusted for. Whenever possible, duplicate initial recordings should be taken to allow determination of and subsequent adjustment for the RTM effect.
本报告的目的是评估两组患者牙周治疗后探诊测量的观察变化相对于均值回归（RTM）的程度。针对与各个位点的初始探诊深度相关的探诊深度和探诊附着水平的观察变化计算回归线。还计算了针对RTM效应进行调整的回归线。对于记录的浅位点和深位点的极端亚组，发现RTM效应（毫米）最大为0.6毫米。在先前评估深位点探诊深度变化的临床研究中得出错误结论的可能性似乎不大，因为RTM在观察到的变化中占比有限。对于浅位点的探诊深度变化以及浅位点和深位点的探诊附着水平变化，RTM在观察到的毫米变化中占比更大。因此，在尚未针对RTM效应进行调整的临床研究中，谨慎解释这些变化似乎是明智的。只要有可能，应进行重复的初始记录，以便确定并随后针对RTM效应进行调整。
