Survival analysis for degree of compliance with supportive periodontal therapy

The purpose of this investigation was to evaluate the degree of compliance for supportive periodontal therapy (SPT) and to determine factors in relation to patients who failed to continue SPT programs.

A sample of 1896 patients who were treated between 1988 and 1999 was studied. The patients were classified by gender, age group and the distance between their house and the hospital. The number of visits was counted based on an electronic patient record for SPT. Data were analyzed by survival analysis. Survival probabilities in SPT were estimated by the Kaplan-Meier method and compared by the generalized Wilcoxon test.

28% of patients did not comply with the first visit for SPT. The older patients had higher tendencies to continue the SPT program than the younger patients. No significant differences in compliance were found between males and females or between short-distance and long-distance groups. However, when these factors were adjusted by age, significantly different patterns were shown on the curves of survival probability: in males, significant differences were found between the 20 s and 30 s (p<0.00001) and between the 50 s and 60 s (p<0.01). In females, significant differences were found between the 40 s and 50 s (p<0.001) and between the 60 s and 70 s (p<0.001). The differences of the survival probability by age group were greater in the short-distance group than in the long-distance group.

The results suggest that age is the most important factor for compliance of the patients with SPT, not only alone but also in relation to the other factors.