Returning to the two key sentences from the Abstract of Lockhart et al,1 the studies linking periodontal disease to cardiovascular disease, to date, are largely association studies. Therefore, sentence 1 is accurate: These studies ...support an association between PD and ASVD independent of known confounders." The issue with association studies is that the association may either accurately or spuriously portray a cause-effect relationship (see Figures 1 and 2). Said differently, association studies generate hypotheses that need to be tested. Sentence 2, however, might be more accurate were it so include two more words: " They do not, however, support [or refute] a causative relationship." In other words, the final word isn't in. A determination of a cause-effect relationship will require an intervention trial, as indicated in the seventh of Hill's postulates. Taken together, this suggests that the rooster(s), perhaps, might consider whether it wants to crow before or after sun up, and the clinical trials are completed, to avoid confusion.
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