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Biostatistics & Research · single question

A study of 2000 people taking bisphosphonates was split into an exercise group and a non-exercise group, to look at the risk of developing MRONJ after dental treatment. 250 of the people who exercised developed MRONJ, and 650 of those who did not exercise developed MRONJ. What can be concluded?

  1. People who take bisphosphonates and exercise have a GREATER risk of developing MRONJ
  2. People who take bisphosphonates and exercise have a LOWER risk of developing MRONJ
  3. Both groups have the same risk of developing MRONJ
  4. People who take bisphosphonates and do NOT exercise have a lower risk of developing MRONJ
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Correct answer: B. People who take bisphosphonates and exercise have a LOWER risk of developing MRONJ

Far fewer of the exercising group developed MRONJ (250) compared to the non-exercising group (650), so exercise is associated with a lower observed risk of MRONJ in this sample — making option B correct. Option A and D reverse the relationship shown by the numbers, and option C is wrong because the two group totals are clearly different. (Note: this describes an association from an observational-style comparison; it does not by itself prove exercise causes lower MRONJ risk — only that the two groups differed in this study.)

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