The effect of different diagnostic thresholds on incidence of disease progression

DETECTION OF PERIODONTAL, DISEASE progression occurs when a predetermined t hreshold of attachment loss is exceeded during longitudinal monitoring. The incidence of disease progression in a population may be dependent on the m ethod and threshold utilized to identify significant changes in attachment level measurements. The aim of this study was to investigate the effect of utilizing different methods and thresholds on the incidence of disease prog ression in an untreated periodontitis population. The relationship between baseline clinical parameters and disease progression was also examined. A t otal of 411 interproximal sites in 46 individuals were monitored monthly ov er a 6-month period. Disease progression was determined by the cumulative s um (CUSUM) method and by the absolute change in relative attachment level b etween months 0 and 6 utilizing 3 different thresholds for attachment level change (0.58 mm, 1.16 mm, and 1.74 mm) based upon examiner repeatability u sing an automated probe. Utilizing the CUSUM method, 49 of 411 sites (11.9% ) demonstrated attachment loss over the B-month observation period. When at tachment level changes greater than or equal to 0.58 mm, greater than or eq ual to 1.16 mm, and 1.74 mm were used to identify disease progression, the percentage of sites exhibiting deterioration were 19.5%, 8.8%, and 2.9%, re spectively. These results demonstrate that the apparent incidence of diseas e progression was dependent on the method and threshold utilized to detect progressive sites. When utilizing the CUSUM and 0.58 mm thresholds a signif icant (P < 0.05), but weak relationship (r = -0.26) was observed between ba seline relative attachment level measurements and sites exhibiting disease progression. This finding suggests that sites with significant but relative ly less attachment loss may be more likely to experience further breakdown compared to sites with a history of greater periodontal destruction.