Kahl B, Fischbach H, Schwarze C W
Department of Orthodontics, University of Cologne, Germany.
Am J Orthod Dentofacial Orthop. 1995 Oct;108(4):415-20. doi: 10.1016/s0889-5406(95)70040-4.
The drop-out in a long-term follow-up study of former orthodontically treated patients was analyzed to avoid biased results. Since structural conformity of the responders (n = 299) and the potential study population (n = 1464) cannot be presumed on the basis of the clinical results, roentgenologic results, and questionnaires, analysis of the participating patients, the follow-up method was used. By means of questionnaires sent to all nonresponders, a comparison of responding and nonresponding patient characteristics was completed to find a presumed selectivity bias. The comparison of the participating patients (n = 299) and the total sample revealed that the responders live closer to the health center, had a longer treatment time, and a shorter posttreatment interval. Compared with nonresponders (n = 266), the responders were satisfied with the treatment result and had a higher dental Intelligence Quotient (IQ, concerning tooth and jaw position). Although a definite answer to the question of validity of the examined subsample was difficult to give, the description and evaluation of the parameters that might be reasons for missing at random respectively, not missing at random was recommended.
对曾接受正畸治疗患者的一项长期随访研究中的失访情况进行了分析，以避免出现有偏差的结果。由于无法根据临床结果、放射学结果和问卷调查来推断应答者（n = 299）与潜在研究人群（n = 1464）在结构上的一致性，因此采用了对参与患者的随访方法。通过向所有未应答者发送问卷，对应答者和未应答者的患者特征进行了比较，以发现可能存在的选择性偏倚。参与患者（n = 299）与总样本的比较显示，应答者居住得离健康中心更近，治疗时间更长，治疗后间隔更短。与未应答者（n = 266）相比，应答者对治疗结果满意，并且具有更高的牙齿智商（IQ，涉及牙齿和颌骨位置）。尽管难以对所检查子样本的有效性问题给出明确答案，但建议对可能分别导致随机失访和非随机失访的参数进行描述和评估。
