## 4 Discussion
[15] study and in our study, the LR+ value was infinite, indicating that a positive result for PD or PI is conclusive. However, in the study by [PERSON] et al. [15], the LR\(-\) was 0.15 (considered good), and in our study, the LR\(-\) was 0.91 (considered bad), indicating that in our study, there were limitations in detecting the presence of disease (Table 4). Using LRs, a Fagan nomogram, which is a graphic representation of the level of reduction in diagnostic uncertainty, can be constructed. \begin{table}
\begin{tabular}{c c c} \hline \hline
**LR+** & **LR\(-\)** & **Utility** \\ \hline
10 & \textless{}0.1 & Highly relevant \\
5–10 & 0.1–0.2 & Good \\
2–5 & 0.5–0.2 & Regular \\ \textless{}2 & \textgreater{}0.5 & Bad \\ \hline \hline \end{tabular}
\end{table} 
Table 4: Utility of a test based on likelihood ratios. In the study by [PERSON] et al. (2015), the subsequent probability was 37%, and in our study, the subsequent probability was 50%. These data indicate that the reduction in uncertainty when considering a healthy individual with a negative test does not exclude the presence of the disease. Again, the differences between the results for the two studies can be explained by the populations studied, i.e., patients with PDs in the study by [PERSON] et al. (2015) and patients with PI in our study. In the study by [PERSON] et al. (2015), the probability that a patient with a negative test presented a PD was 37%. In our study, the probability that a patient with PI had a negative test was 50%. These values are useful in determining the diagnostic power of the test ([PERSON] et al., 2016). Recommended values are provided in the following table. A negative probability ratio (LR\(-\)) of 0.91, which is less than 0.5, indicated that the test has limited utility in ruling out the presence of PI. Therefore, Periopoc(r) can serve as a confirmatory test for patients with clinically and radiographically confirmed PI, but it is not valid for screening individuals for the presence of PI. [PERSON] theorem and pretest probability can be converted into a linear graph or Fagan nomogram ([PERSON] et al., 2016). Haga clic o pulse aqui para escribir texto. A Fagan nomogram has three columns: pretest probability, that is, the probability of having the disease before performing the test; likelihood ratio; and post-test probability. A straight line is drawn from the pretest probability value to the likelihood ratio, and the point at which the line crosses into the third column represents the probability of having the disease based on the test result ([PERSON] et al., 2016). In this study, a line was drawn from the 52% pretest probability (prevalence of PI in our sample) toward infinity (positive likelihood ratio), and another line was drawn from the pretest probability to the negative likelihood ratio of 0.91, indicating that the post-test probability was 50%. Based on the Fagan nomogram, for 100% of patients who are sick and tested, only 50% of those who test positive will be truly ill with PI and proceed to treatment. The status of the other 50% will remain uncertain. Therefore, Periopoc(r) is an effective tool when yielding positive test results because the result correctly identifies patients with PI who need to be treated. However, a large number of patients with PI with negative test results will require more tests for the diagnosis of this pathology. Finally, this new qualitative test is an inefficient alternative to quickly diagnose a pathology that requires other tests for a certain diagnosis. The results of this study indicate that Periopoc(r) may be insufficient for the identification of the five main pathogens of the peri-implant sulcus. The test had low sensitivity but high specificity. Therefore, this test is effective as a test to confirm a diagnosis of PI; however, a negative result does not rule out the presence of PI.