Cunningham Devin P, Mostafa Ayman A, Gordan-Evans Wanda J, Boudrieau Randy J, Griffon Dominique J
Western University of Health Sciences, Pomona, CA, 91766, USA.
, University of Missouri, Columbia, MO, USA.
BMC Vet Res. 2017 Aug 14;13(1):235. doi: 10.1186/s12917-017-1154-9.
We recently reported that a conformation score derived from the tibial plateau angle (TPA) and the femoral anteversion angle (FAA), best discriminates limbs predisposed to, or affected by cranial cruciate ligament disease (CCLD), from those that are at low risk for CCLD. The specificity and sensitivity of this score were high enough to support further investigations toward its use for large-scale screening of dogs by veterinarians. The next step, which is the objective of the current study, is to determine inter-observer variability of that CCLD score in a large population of Labrador Retrievers. A total of 167 Labradors were enrolled in this cross-sectional study. Limbs of normal dogs over 6 years of age with no history of CCLD were considered at low risk for CCLD. Limbs of dogs with CCLD were considered at high risk for CCLD. Tibial plateau and femoral anteversion angles were measured independently by two investigators to calculate a CCLD score for each limb. Kappa statistics were used to determine the extent of agreement between investigators. Pearson's correlation and intraclass coefficients were calculated to evaluate the correlation between investigators and the relative contribution of each measurement to the variability of the CCLD score.
The correlation between CCLD scores calculated by investigators was good (correlation coefficient = 0.68 p < 0.0001). However, interobserver agreement with regards to the predicted status of limbs was fair (kappa value = 0.28), with 37% of limbs being assigned divergent classifications. Variations in CCLD scores correlated best with those of TPA, which was the least consistent parameter between investigators. Absolute interobserver differences were two times greater for FAAs (4.19° ± 3.15) than TPAs (2.23° ± 1.91).
The reproducibility of the CCLD score between investigators is fair, justifying caution when interpreting individual scores. Future studies should focus on improving the reproducibility of TPA and FAA measurements, as strategies to improve the agreement between CCLD scores.
我们最近报告称，由胫骨平台角（TPA）和股骨前倾角（FAA）得出的构象评分，能最好地区分易患或已患颅交叉韧带疾病（CCLD）的肢体与CCLD低风险肢体。该评分的特异性和敏感性足够高，足以支持进一步研究其供兽医用于大规模犬类筛查的用途。下一步，即本研究的目的，是确定在大量拉布拉多寻回犬群体中该CCLD评分的观察者间变异性。共有167只拉布拉多犬纳入了这项横断面研究。6岁以上无CCLD病史的正常犬的肢体被视为CCLD低风险肢体。患有CCLD的犬的肢体被视为CCLD高风险肢体。两名研究者分别测量胫骨平台角和股骨前倾角，以计算每个肢体的CCLD评分。使用kappa统计量来确定研究者之间的一致程度。计算Pearson相关性和组内系数，以评估研究者之间的相关性以及每次测量对CCLD评分变异性的相对贡献。
研究者计算的CCLD评分之间的相关性良好（相关系数 = 0.68，p < 0.0001）。然而，观察者间关于肢体预测状态的一致性一般（kappa值 = 0.28），37%的肢体被赋予了不同的分类。CCLD评分的变化与TPA的变化相关性最佳，而TPA是研究者之间最不一致的参数。FAA的观察者间绝对差异（4.19°±3.15）是TPA（2.23°±1.91）的两倍。
研究者之间CCLD评分的可重复性一般，在解释个体评分时需谨慎。未来的研究应侧重于提高TPA和FAA测量的可重复性，作为提高CCLD评分之间一致性的策略。
