Odds ratio (OR) for the progression of attachment loss (AL) according to leukotoxicity.

Cell lysis (minimal = 0–30%, average + high = ≥31% release of cytosolic LDH), Cell death (minimal + average = 0–60%, high = ≥61% reduction of viable cells), Haemolysis (1 = minimal, none or small zone, 2 = average, average size zone, 3 = high, large size zone). Subgroup of individuals (n = 146) positive for A. actinomycetemcomitans. The reference group consisted of individuals (n = 190) who were negative for A. actinomycetemcomitans. OR, odds ratio; confidence interval; AL, attachment loss. Significance (p*A.a; A. actinomycetemcomitans.