Given a passage, construct a question on the basis of the information present in the passage. Construct the question in such a way that (i) it is unambiguous, (ii) it is answerable from the passage, (iii) its answer is unique (iv) it answer uses text phrases from the passage. Avoid creating questions that (i) can't be answered correctly without actually understanding the passage and (ii) uses the same words or phrases given in the passage.

[Q]: Beta blockers and calcium antagonists are widely used in the management of angina pectoris in the belief that the combination is more efficacious than either drug alone.', 'This double blind randomised crossover placebo controlled study compares the effects of nicardipine, atenolol and their combination in 30 patients with chronic stable angina. Each treatment period lasted 6 weeks with dose titration after 3 weeks. Symptom limited treadmill exercise testing and radionuclide ventriculography at rest was carried out at the end of each treatment period.', 'Total exercise duration and time to 1-mm ST-segment depression was significantly prolonged by nicardipine and atenolol when compared to placebo, the combination offered no additional benefit. Time to onset of angina was significantly prolonged by nicardipine and the combination but not by atenolol. Indices of left ventricular function were not significantly affected by any treatment other than an increase in left ventricular end diastolic volume on atenolol and the combination.
[A]: Is atenolol or nicardipine alone as efficacious in stable angina as their combination : a double blind randomised trial?

[Q]: Studies performed in Andean populations living in high altitude, indicate that the reduced availability of oxygen could be associated to both a fetal growth retardation and a lower birth weight. These variables are predictive of morbidity and mortality during the first year of life.', 'To study perinatal variables of newborns of mothers living at contrasting altitudinal levels, harboring different degrees of Aymara ancestry.', 'Review of medical records of 5,295 women whose deliveries occurred between February 2004 and August 2010. Information was obtained on place of residence, grouped into two categories: coast (150 to 3,000 m) and high plateau (3,000 to 4,300 m), ancestry was estimated using number of Aymara surnames that were homologated to percentages of Amerindian admixture, gestational age, birth weight, height, head circumference and obstetric variables.', 'Gestational age showed a tendency to increase and birth weight, height and head circumference to decrease with altitude of residence. Only weight reached statistical significance. Women with Aymara ancestry gave birth to children with a significantly higher gestational age, weight and cranial circumference.
[A]: Do [ Perinatal variables from newborns of Aymara mothers suggest a genetic adaptation to high altitude ]?

[Q]: Crohn's disease is associated with a host of factors potentially increasing the risk for osteoporosis and fractures. The aim of our study was to identify the most predictive factors for skeletal pathology in this patients.", "Using a cross-sectional study design, 146 randomly selected patients with Crohn's disease of variable disease activity who were given standard therapy to control disease activity, including glucocorticoids, and who attended the outpatient clinic of the Gastroenterology Unit on regular follow-up visits were studied. Bone mineral density (BMD) measurements and lateral X-rays of the spine were performed, and biochemical parameters of bone turnover, gonadal hormones and C-reactive protein (CRP) as markers of disease activity were measured in all patients.", 'There were 61 men and 85 women, with a mean age of 43 years and mean disease duration of 20 years. The majority of patients (86%) had been treated with glucocorticoids at some stage during their illness at a median dose of 7.5 mg/day, 43% were currently using these agents and 66% had undergone an intestinal resection. Twenty-one percent of patients had below-normal 25-hydroxy vitamin D levels. Osteoporosis was documented in 26% of patients, predominantly at the femoral neck, but also at the lumbar spine or at both sites; osteopenia was documented in 45% of patients. Prevalence of vertebral and non-vertebral fractures was, respectively, 6% and 12%. Ileum resection was the most predictive factor for osteoporosis: RR 3.84 (CI 1.24-9.77, p=0.018), followed by age: RR 1.05 (CI 1.02-1.08, p<0.001) and current or past glucocorticoid use: RR 1.94 (CI 0.92-4.10, p=0.08).
[A]:
Is ileum resection the most predictive factor for osteoporosis in patients with Crohn 's disease?