# Randomized trial of dentists’ understanding: treatment benefit in absolute numbers vs relative risk reduction

## TL;DR

This study found that most dentists struggle to understand treatment benefits, with slightly better performance when information is presented as absolute numbers rather than relative risk reduction.

## Contribution

The study provides new evidence on how dentists interpret treatment benefits using different statistical formats.

## Key findings

- Most dentists did not correctly understand treatment benefits regardless of the presentation format.
- Slightly more dentists correctly understood benefits when presented as absolute numbers compared to relative risk reduction.
- Only 31% of dentists in the absolute numbers group answered both questions correctly.

## Abstract

This study aimed to assess whether dentists correctly understand the benefit of a dental treatment when it is presented using absolute numbers or relative risk reduction (RRR). This parallel-group randomized controlled trial recruited dentists from 3 postgraduate courses in Rio de Janeiro, Brazil. Participants received, in sequentially numbered sealed opaque envelopes, the description of a hypothetical scenario of the benefit (avoidance of multiple tooth loss) of nonsurgical periodontal treatment without or with antibiotics. Treatment benefit was presented in 2 different formats: absolute numbers or RRR. Dentists were given 10 minutes to read the treatment scenario and answer 5 questions. The final sample for analysis included 101 dentists. When asked to estimate the number of patients out of 100 who would avoid multiple tooth loss without antibiotics, 17 dentists (33%) in the absolute numbers group and 12 (25%) in the RRR group provided the correct response (p = 0.39). Regarding treatment with antibiotics, 26 dentists (50%) in the absolute numbers group and 14 (29%) in the RRR group provided the correct response (p = 0.04). Only 16 dentists (31%) in the absolute numbers group and 12 (25%) in the RRR group gave correct answers for both questions (p = 0.51). Most dentists did not correctly understand the benefit of the treatment, irrespective of the format it was presented. Slightly more dentists correctly understood the benefit of the treatment when it was presented as absolute numbers than as RRR.