A 12-year-old boy with sickle cell disease and type 1 diabetes mellitus is brought to the office by his mother for an initial visit. The family recently moved to the area. Type 1 diabetes mellitus was diagnosed in the patient 6 years ago. Since that time, he has been treated with insulin and dietary management. His insulin regimen has not changed during the past year; however, his mother says he has been only marginally compliant with his insulin and dietary regimens. His diabetic diary shows home fingerstick blood glucose concentrations ranging from 140–200 mg/dL during the past 3 months. He admits to checking his glucose concentrations infrequently. Measurement of hemoglobin A1c obtained last week was 5.4%. The patient’s vital signs are temperature 36.8°C (98.2°F), pulse 72/min, respirations 24/min, and blood pressure 110/64 mm Hg. Physical examination shows no abnormalities. Which of the following is the most likely explanation for the discrepancy between the patient’s home fingerstick blood glucose concentrations and his hemoglobin A1c?
- (A) He has iron deficiency anemia
- (B) His daily glucose control is better than recorded
- © His glucometer is reading falsely high and should be replaced
- (D) His hemoglobin A1c is likely a result of laboratory error and should be repeated
- (E) His sickle cell disease is affecting his hemoglobin A1c
- A phase 2, multicenter trial was conducted to determine the efficacy of a new vaccine for prevention of HIV infection. The study enrolled 4000 subjects, aged 20 to 65 years. Of these subjects, 2100 were men and 1900 were women; 2500 were white, 1000 were African American, 300 were Hispanic, and 200 were Asian/Pacific Islanders. Results of the trial showed no overall benefit of the vaccine. However, post hoc analysis disclosed a small but statistically significant vaccine protection among African American subjects. Which of the following is the most accurate rationale for questioning the validity of efficacy analysis of the HIV vaccine among the African American study subjects?
- (A) Allocation bias favored African American subjects
- (B) HIV infection is more prevalent among African American populations
- © The study was not blinded
- (D) There was a Type II error
- (E) Vaccine response among African American subjects was not the primary outcome measure