A patient's mother comes to you with a prospective cohort study linking autism to the measles, mumps and rubella vaccine. After reviewing the study carefully, you question the results because of problems with the study design and execution. Which one of the following sources of error would be most important in the study design or execution? 

You performed a surgical procedure on a 32-year-old woman for a herniated disk that was causing neurologic impairment. At the 8-month follow-up visit, she has healed well; however, she requests a prescription renewal of her narcotic analgesics (hydromorphone). Her pharmacy confirms that the patient adheres to the dosage you prescribed, that she has not consulted other physicians, and that her behavior has always been respectful. You think that she no longer requires narcotic analgesics. Which one of the following approaches is most helpful to the patient?

A 34-year-old woman, gravida 3, para 2, aborta 0, presents at 38 weeks' gestation. She is in early labor with ruptured membranes. Her previous pregnancy was complicated by fever during labor. Which one of the following would increase the risk of fever recurrence?

A 32-year-old woman, gravida 0, comes to your office for contraception counselling, specifically about insertion of a levonorgestrel-releasing intrauterine device. She has a past history of breast cancer and is presently on tamoxifen. Which one of the following is the best advice for your patient? 

A 43-year-old man comes to your office for the first time. He has not seen a doctor in over 5 years and has no known past medical history. On examination, his blood pressure is 120/70 mm Hg, and the remainder of his examination is normal. As part of the initial visit, you order some screening blood work that reveals a fasting blood glucose of 6.3 mmol/L (3.3–5.8) and a hemoglobin A1c of 6.1% (4–6). Which one of the following is the best next step?