Application of Causation Principles in Clinical Practice

Case Scenario
How to use the principles of causality when patients pose questions they have heard through the media.

George, a 55-year old male patient, whom you have not seen in 2 years, comes in for an examination. Upon observation, he appears to have gained substantial weight and claims he is still a smoker, despite efforts to quit. He appears to be a bit out of breath and when you take his blood pressure, you find it is elevated (150/90) despite taking daily medication for his hypertension (enalapril, 15mg OD). He reveals he has also recently started taking medication for high cholesterol (atorvastatin, 20 mg OD) as it seems to have gone out of control this past year. Upon oral examination, you note that his gingival tissues have generalized inflammation and when you measure his periodontal pocket depths, you find his readings have increased significantly since his last visit. Pocket depth measurements in all 4 quadrants have readings ranging from 5-7 mm, with one area in the maxillary molar region having 2 degrees of mobility along with an 8mm pocket that has trifurcation involvement. Radiographic examination confirms there is significant bone loss in several areas of his mouth. You inform George that he has moderate generalized chronic periodontitis with one area of localized advanced chronic periodontitis. You go on to explain that smoking is a risk factor and one of the causes of periodontal disease and it would be very important for him to enroll in a smoking cessation program to try to stop smoking and halt the progression of his periodontal disease.

George becomes very alarmed with this information and goes on to say that he has heard from a friend and also found information on the internet, that periodontal disease causes heart disease! He asks you if this is true and is he at risk?

Using your knowledge of the Bradford Hill Criteria, how would you go about answering this question?

“Will my periodontal disease cause me to have heart disease?”

Published RCT’s, Cohort Studies or Systematic reviews (showing temporality)? Yes No
Strength of the evidence for this claim? OR's RR's
What were the outcomes of the studies? >2 <2
Were the findings of the studies consistent? Yes No
What about specificity of periodontal disease affecting heart disease? Yes No
What about dose-response? The more severe the disease, the higher the risk?? Yes No
What about biological plausibility? Do you think it is plausible?? Yes No
Experiment (were there experimental studies?? (i.e., RCT’s) Yes No
Analogy (have there been any animal /lab studies showing this to be true??) Yes No