Evaluating clinical periodontal measures as surrogates for bacterial exposure: The Oral Infections and Vascular Disease Epidemiology Study (INVEST)

Table 4 Correlations between Bacterial Burden and Selected Clinical Periodontal Constructs (n = 706)

	Attachment Loss Extent Constructs				Pocket Depth Extent Constructs
Severity Threshold	*#AL ≥ Threshold*	%AL ≥ Threshold	*Sum AL ≥ Threshold*	Mean AL ≥ Threshold	*#PD ≥ Threshold*	%PD ≥ Threshold	*Sum PD ≥ Threshold*	Mean PD ≥ Threshold
2 mm	0.39 (A,C)	0.48 (A)	0.47 (A)	0.30 (A)	0.16 (A,E,F)	0.42 (A)	0.40 (A,C)	0.49 (A)
3 mm	0.48 (B)	0.48 (A)	0.46 (A)	0.21 (B)	0.51 (B)	0.61 (B)	0.48 (B)	0.25 (B,D)
4 mm	0.40 (A)	0.30 (B)	0.38 (B)	0.27 (A)	0.39 (C)	0.39 (A)	0.39 (A)	0.34 (C)
5 mm	0.39 (A)	0.29 (B)	0.34 (C)	0.23 (B)	0.39 (C)	0.38 (A)	0.35 (C)	0.28 (D)
6 mm	0.33 (C)	0.26 (B)	0.29 (D)	0.25 (B)	0.28 (D)	0.26 (C)	0.24 (D)	0.27 (D)
7 mm	0.29 (D)	0.23 (C)	0.25 (E)	0.26 (A,B)	0.18 (E)	0.20 (D)	0.19 (E)	0.18 (E)
8 mm	0.28 (D)	0.24 (B,C)	0.23 (F)	0.24 (A,B)	0.14 (F)	0.16 (D)	0.15 (F)	0.15 (E)

Bacterial burden is the dependent variable for all 56 correlations presented. All 56 correlation coefficients are statistically significantly different than zero (p-value < 0.0001 for null hypothesis Ho: ρ = 0). Pairwise comparisons were performed between all seven correlation coefficients within each extent periodontal construct (represented in columns), to see if severity threshold impacted strength of correlation (Ho: ρ_1i = ρ_2i,); coefficients that do not share a common letter are statistically significantly different (p < 0.05) - based on methods for comparing correlated correlation coefficients from Meng et al.(Meng et al. 1992) For example, the correlation between bacterial burden (the common dependent variable) and %PD ≥ 3 mm (r = 0.61) is statistically significantly different than the correlation between bacterial burden and %PD ≥ 4 mm (r = 0.39).

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