Given a passage with a context and an answer, 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.

[EX Q]: Context: To assess, in a retrospective cohort, urinary tract urothelial carcinoma (UT-UC) in patients with various stages of chronic kidney disease (CKD) and their clinicopathological features, as patients with end-stage renal disease (ESRD) have a higher incidence of UT-UC, but the relationship between early stages of CKD and characteristics of UT-UC are less well known.', 'The study included 267 patients with pathologically confirmed UT-UC from January 1994 to December 2006; all had a physical examination (blood pressure), and measurements of laboratory data (serum creatinine, serum haemoglobin) and pathological data. The glomerular filtration rate (GFR) was calculated using the Modification of Diet in Renal Disease equation. Patients were divided into three groups by individual GFR (mL/min), i.e. >60 (no/mild CKD), 30-60 (CKD stage 3) and <30 (CKD stage 4/5).', 'The CKD stages included 81 (30.3%) patients with none/mild CKD, 121 (45.3%) with CKD stage 3 and 65 (24.3%) with CKD stage 4/5. There was a significant and parallel increase in the frequency of UT-UC as CKD severity increased from none/mild CKD to stage 3 (11% vs 55%), and from CKD stage 3 to 4/5 (55% vs 71%; P < 0.05). Pathologically, the frequency of high-grade and high T stage UT-UC in patients with CKD stage 3 (90% and 35%, respectively) and CKD stage 4/5 (91% and 29%, respectively) were significantly greater than in the group with none/mild CKD (P < 0.001). Advanced age and more distant metastasis were independent risk factors for patient survival.
Answer: The aggressiveness of UT-UC increased with the severity of CKD, and this might have important clinical consequences.
[EX A]: Does the aggressiveness of urinary tract urothelial carcinoma increase with the severity of chronic kidney disease?

[EX Q]: Context: Patients with chronic heart failure (CHF) have multiple abnormalities of autonomic regulation that have been associated to their high mortality rate. Heart rate recovery immediately after exercise is an index of parasympathetic activity, but its prognostic role in CHF patients has not been determined yet.', 'Ninety-two stable CHF patients (83M/9F, mean age: 51+/-12 years) performed an incremental symptom-limited cardiopulmonary exercise testing. Measurements included peak O2 uptake (VO2p), ventilatory response to exercise (VE/VCO2 slope), the first-degree slope of VO2 for the 1st minute of recovery (VO2/t-slope), heart rate recovery [(HRR1, bpm): HR difference from peak to 1 min after exercise] and chronotropic response to exercise [%chronotropic reserve (CR, %)=(peak HR-resting HR/220-age-resting HR)x100]. Left ventricular ejection fraction (LVEF, %) was also measured by radionuclide ventriculography.', 'Fatal events occurred in 24 patients (26%) during 21+/-6 months of follow-up. HRR1 was lower in non-survivors (11.4+/-6.4 vs. 20.4+/-8.1; p<0.001). All cause-mortality rate was 65% in patients with HRR1<or=12 bpm versus 11% in patients with HRR1>12 bpm (log-rank: 32.6; p<0.001). By multivariate survival analysis, HRR1 resulted as an independent predictor of mortality (chi2=19.2; odds ratio: 0.87; p<0.001) after adjustment for LVEF, VO2p, VE/VCO2 slope, CR and VO2/t-slope. In a subgroup of patients with intermediate exercise capacity (VO2p: 10-18, ml/kg/min), HRR1 was a strong predictor of mortality (chi2: 14.3; odds ratio: 0.8; p<0.001).
Answer: Early heart rate recovery is an independent prognostic risk indicator in CHF patients and could be used in CHF risk stratification.
[EX A]: Does early heart rate recovery after exercise predict mortality in patients with chronic heart failure?

[EX Q]: Context: Elevated blood lead levels (BLL) and malaria carry an important burden of disease in West Africa. Both diseases might cause anemia and they might entail long-term consequences for the development and the health status of the child. Albeit the significant impact of malaria on lead levels described in Nigeria, no evaluation of the effect of elevated BLL on malaria risk has been investigated so far.', 'Between 2010 and 2012, blood lead levels of 203 Beninese infants from Allada, a semi-rural area 50km North from Cotonou, were assessed at 12 months of age. To assess lead levels, blood samples were analyzed by mass spectrometry. In parallel, clinical, microbiological and hematological data were collected. More precisely, hemoglobin, serum ferritin, CRP, vitamin B12, folate levels, and Plasmodium falciparum parasitemia were assessed and stool samples were also analyzed.', 'At 12 months, the mean BLL of infants was 7.41 μg/dL (CI: 65.2; 83), and 128 infants (63%) had elevated blood lead levels, defined by the CDC as BLL>5 μg/dL. Lead poisoning, defined as BLL>10 μg/dL, was found in 39 infants (19%). Twenty-five infants (12.5%) had a positive blood smear at 12 months and 144 infants were anemic (71%, hemoglobin<110 g/L). Elevated blood lead levels were significantly associated with reduced risk of a positive blood smear (AOR = 0.38, P-value = 0.048) and P. falciparum parasite density (beta-estimate = -1.42, P-value = 0.03) in logistic and negative binomial regression multivariate models, respectively, adjusted on clinical and environmental indicators.
Answer: Our study shows for the first time that BLL are negatively associated with malarial risk considering other risk factors. Malaria is one of the main causes of morbidity and mortality in infants under 5 years worldwide, and lead poisoning is the 6th most important contributor to the global burden of diseases measured in disability adjusted life years (DALYs) according to the Institute of Health Metrics. In conclusion, due to the high prevalence of elevated BLL, health interventions should look forward to minimize the exposure to lead to better protect the population in West Africa.
[EX A]:
Do elevated Blood Lead Levels Are Associated with Reduced Risk of Malaria in Beninese Infants?