Factors Predictive of Orthodontic Patient in-Treatment Compliance, and Final Outcome

Objectives: A clearer understanding of factors associated with patient’s compliance during orthodontic treatment and the quality of final treatment outcome is important for both clinicians and patients. The project was aimed at assessing the relationships among several pretreatment factors and final orthodontic treatment outcome.
Methods: Following predesigned inclusion and exclusion criteria, orthodontic records of 309 patients treated at The Ohio State University orthodontic clinic were used. Data of 7 pretreatment factors (age, sex, race, socioeconomic status, oral-hygiene, initial PAR score, severity of orthodontic problem) were collected. Based on designed criteria, in-treatment compliance was classified into three levels by two independent raters though reviewing treatment notes. Treatment outcome was also graded into three levels by evaluating absolute final PAR score and relative PAR score reduction. Reliability of compliance, outcome classification and PAR scoring was tested by Cohen’s Kappa and intra-class correlation (ICC) tests, respectively. Ordinal logistic regression models were employed to test factors predictive of in-treatment compliance and factors predictive of final outcome.
Results: Intra-rater reliability of PAR scoring was over 0.9 (ICC) and inter-rater reliability of compliance and outcome classifications was over 0.7 (Kappa). Ordinal logistic regression demonstrated that declining in-treatment compliance was significantly correlated with worsening of oral-hygiene status (p=0.026, odds ratio 1.50) and increase of initial PAR score (p<0.001, odds ratio 1.05). Declining in in-treatment compliance was significantly correlated with worsening of treatment outcome, in both absolute final PAR (p=0.016, odds ratio 1.47) and relative PAR score reduction (p=0.032, odds ratio 1.46).
Conclusions: Poor in-treatment compliance may lead to lowered quality of treatment outcome while poor initial oral hygiene may be a predictor for inferior in-treatment compliance.