Long-term Comparative Effectiveness of 2 Treatments to Arrest Dental Caries in Older Adults

Study Design: The original design was a cluster randomized clinical trial (RCT) in 33 publicly subsidized housing facilities/sites in NE Ohio and housing sites randomized into 2 arms in a roughly 1:1 ratio (SDF vs. ART + FV) and is a continuation of the original study "Reducing Oral Health Disparities of Older Adults: Comparative Effectiveness of 2 Treatments". All participants will be followed for one year and will receive intervention when new decay is present. The study hypothesis for the LTFU study is noninferiority of SDF to ART + FV for each of the primary outcomes. Primary outcomes are assessed through clinical and questionnaire evaluations. We will maintain blinding of participants to the study arm. Other clinical and study staff cannot be blinded due to the nature of the interventions.

Study Population and Setting: For the Intervention Arm, a total of 287 participants from 18 facilities will receive biannual 38% SDF, and for the Control Arm, a total of 193 participants from 15 facilities will receive ART + biannual FV application for new decay. Housing sites are located in three counties in Northeast Ohio (Cuyahoga, Summit, and Lorain). IRB approval was given allowing study staff to contact participants from the original study for future studies. Informed consent for LTFU will be obtained in-person at scheduled "Dental Days" at the housing sites. These will be scheduled in coordination with the housing site Service Coordinators, who will be briefed well in advance of LTFU activities.

A total of 480 participants (out of 568 from the original study) are expected to be retained into the LTFU study. Among the 480 participants to be consented and enrolled in the long-term follow-up, 26% (n-124), 36% (n=173), 17% (n=82), 21% (101) will contribute data at 3, 4, 5, 6 years post-randomization respectively. Each participant will be followed for one year (total of 3 visits -baseline (LTFU #1), 26 weeks (LTFU #2), 52 weeks (LTFU #3).The study population are predominantly low socioeconomic status (SES) and are adults ≥ 62 years of age residing in 33 participating HUD Section 202 and other publicly subsidized housing facilities. The population is diverse: African American/Black, Caucasian/White including Hispanic/Latino, and Asian. Medicaid participation among the tenants is 76% among facilities. The characteristics of the 480 in this long-term follow-up vs. the 568 participants that completed the cRCT are similar as follows: mean age 69.5±6.6 vs. 69.6±6.8; female 52% vs. 51%; Hispanic 2.9% vs. 2.7%; black 66% vs. 66%, white 29.6% vs. 29.3%; high school education or less 57% vs. 57.2%; living alone 93.7% vs. 93.3%; annual income $12, 490 or less 53.4% vs. 53.1%. Bi-variate analysis of the 480 LTFU participants vs. 88 non-participants indicate no significant differences in any of the characteristics indicating representativeness of the LTFU study population. These participants are also a diverse representation of the overall population in NE Ohio.

Analytic Plan: Analyses will follow the intent-to-treat principle; namely, the SDF and ART groups to be compared will be defined according to the randomization of sites (and original site residency of individuals). Preliminary analyses will involve the construction of one-sided 95% confidence interval based on a t-test (or other appropriate test) for the difference in mean responses (ART minus SDF) at selected long-term follow-up times. To account for clustering, a modified approach for these t-tests to allow for a possible non-zero within-facility correlation will be used. If this confidence interval lies below (for an outcome where higher is better) or above (where lower is better) the tolerance value then we may make the preliminary conclusion of 'non-inferiority' of SDF relative to ART with respect to that outcome. Confidence intervals will also be used to determine superiority of one intervention relative to the other.

To corroborate initial results, we will conduct generalized estimating equations (GEE) analyses. Specifically, for each outcome at the targeted long-term follow-up time, we will fit a GEE (marginal) model including, as covariates, an indicator variable for treatment and a selected set of baseline variables (including sociodemographic - e.g., race, gender and age, medical conditions, and oral health behavior variables) that are prognostic for the given outcome. Appropriate link functions will be used: a logit link for binary or binomial outcomes (including the arrest rate), a log link for count outcomes (number of newly missing teeth and number of newly decayed teeth), and an identity link for continuous outcomes (tooth pain score and GOHRQoL). An exchangeable working correlation matrix will be used to account for correlations among subjects within site. Inferiority and superiority (based on appropriate - possibly scale-transformed - tolerance values) will be tested using robust t tests with correction for a small number of clusters (or via corresponding 95% confidence intervals).