Clinical benefits of systemic amoxicillin/metronidazole may depend on periodontitis severity and patients' age: An exploratory sub-analysis of the ABPARO trial

Abstract

Aim: The aim was to identify benefit thresholds for clinical variables. We hypothesize, if variables fall below or exceed these threshold levels, systemic amoxicillin/metronidazole may contribute to reducing progression of periodontitis.

Material & methods: This is an explorative per-protocol collective analysis (n = 345) conducted on the placebo-controlled, multi-centre ABPARO trial (ClinicalTrials.gov NCT00707369). Patients received debridement with systemic amoxicillin 500 mg/metronidazole 400 mg (3×/day, 7 days, n = 170) or placebo (n = 175) and maintenance therapy every three months. To identify thresholds, each of the following baseline characteristics was classified into two groups (≥threshold value/<threshold value): bleeding on probing, extent of pocket probing depth (PPD) ≥ 5 mm, mean clinical attachment level and age. Treatment effect (% of sites with new attachment loss ≥ 1.3 mm at 27.5 months post-treatment) was calculated.

Results: Adjunctive antimicrobials reduced median new attachment loss in patients < 55 years (5.2%), or with ≥ 35% PPD ≥ 5 mm (4.5%) or with a mean attachment level > 5 mm (5.2%) at baseline compared to the placebo (9.0%, 11.6%, and 12.5%, respectively; p < 0.005).

Conclusions: The clinical benefits of systemic amoxicillin/metronidazole may depend on periodontitis severity and patients' age.

Keywords: amoxicillin/metronidazole; attachment loss; clinical threshold; periodontitis; systemic antimicrobials.

Conflict of interest statement

The authors have explicitly stated that no conflicts of interest exist in connection with this article.

© 2019 The Authors. Journal of Clinical Periodontology published by John Wiley & Sons Ltd.

Figures

Figure 1

Scatterplots of clinical and demographic baseline parameters in relation to the proportion of new attachment loss (PSAL) ≥ 1.3 mm after 27.5 months for the antimicrobial group (▲) and placebo group (●). Lines represent fitted, locally weighted regression (LOESS) curves using linear interpolation and optimal smoothing parameters based on the AICC criterion. A descriptive clinical threshold was identified for the proportion of sites that exhibit pocket probing depths ≥ 5 mm (a), for age (b) and mean attachment level at baseline (c) (dashed orange line, respectively). No threshold could be identified for initial bleeding on probing (d)

Figure 2

Boxplots of the proportion of new attachment loss ≥ 1.3 mm in the antimicrobial group () and placebo group () in: (a) patients falling below (<35%) or exceeding (≥ 35%) the baseline threshold (%) of pocket probing depth ≥ 5 mm, (b) patients falling below (≤55 years) or exceeding (>55 years) the baseline age threshold and (c) patients falling below (<5 mm) or exceeding (≥ 5 mm) the baseline attachment level threshold. X refers to the mean

Figure 3

Boxplots of the proportion of new attachment loss ≥ 1.3 mm in the antimicrobial group () and placebo group () in patients falling below or exceeding the combined baseline thresholds identified for pocket probing depth ≥ 5 mm (%) and the age threshold. X refers to the mean