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.

[EX Q]: Although the majority of evidence does not support association between Helicobacter pylori infection and ischaemic heart disease, the nature of this relationship may differ when virulence of the infecting strains are examined.', 'The prevalence of IgG antibody evidence of infection with CagA positive stains of H. pylori was investigated in stored plasma samples from 259 cases of myocardial infarction (aged 25-70 years, 74 males) and 259 population based controls from the same area in Northern Ireland. Two-hundred and seventy (52.1%) subjects were seropositive for anti-CagA IgG. CagA seropositivity was more common in cases than in controls: 56.4 vs 47.9%, odds ratio for seropositivity in cases (95% CI) 1.41 (1.00, 1.99). Substantial attenuation of this relationship occurred on adjustment for age, sex, number of siblings, smoking and measures of socio-economic status: odds ratio (95% CI) 1.16 (0.79, 1.70). A similar pattern was seen for seropositivity for all H. pylori strains.
[EX A]: Is infection with virulent strains of Helicobacter pylori associated with ischaemic heart disease : evidence from a population-based case-control study of myocardial infarction?

[EX Q]: The purpose of this research study was to identify factors that are associated with receiving care in a medical home for children with special health care needs (CSHCN) and to identify how these factors vary among different socioeconomic levels.', 'Data were obtained from the National Survey of Children with Special Health Care Needs, 2000-2002. Access to a medical home was derived using an algorithm. This survey analysis also included demographic characteristics, geographical location of household, severity of condition, and social factors. Multiple logistic regression models were constructed for socioeconomic status (SES) levels defined by federal poverty level (FPL): <133%; 133-199%; 200-299%; > or =300%.', 'Age group was significant in all but the 200-299% of FPL stratum. Severity of condition was significant in all strata. Race was significant in all but the > or =300% stratum. Maternal education was borderline significant in the lowest and highest strata. Insurance type/status was significant in all but the 133-199% of FPL stratum. Geographical location was significant in the lowest and highest strata. The language of the interview was only significant in the lowest stratum. The relationship of the respondent to the child was significant in the middle two strata. The total number of adults in the household was significant in the highest stratum, and the total number of children in the household was significant in the 200-299% of FPL stratum.
[EX A]: Do factors for accessing a medical home vary among CSHCN from different levels of socioeconomic status?

[EX Q]: Passive leg raising (PLR) represents a "self-volume challenge" that could predict fluid response and might be useful when the respiratory variation of stroke volume cannot be used for that purpose. We hypothesized that the hemodynamic response to PLR predicts fluid responsiveness in mechanically ventilated patients.', 'Prospective study.', 'Medical intensive care unit of a university hospital.', 'We investigated 71 mechanically ventilated patients considered for volume expansion. Thirty-one patients had spontaneous breathing activity and/or arrhythmias.', 'We assessed hemodynamic status at baseline, after PLR, and after volume expansion (500 mL NaCl 0.9% infusion over 10 mins).', 'We recorded aortic blood flow using esophageal Doppler and arterial pulse pressure. We calculated the respiratory variation of pulse pressure in patients without arrhythmias. In 37 patients (responders), aortic blood flow increased by > or =15% after fluid infusion. A PLR increase of aortic blood flow > or =10% predicted fluid responsiveness with a sensitivity of 97% and a specificity of 94%. A PLR increase of pulse pressure > or =12% predicted volume responsiveness with significantly lower sensitivity (60%) and specificity (85%). In 30 patients without arrhythmias or spontaneous breathing, a respiratory variation in pulse pressure > or =12% was of similar predictive value as was PLR increases in aortic blood flow (sensitivity of 88% and specificity of 93%). In patients with spontaneous breathing activity, the specificity of respiratory variations in pulse pressure was poor (46%).
[EX A]:
Does passive leg raising predict fluid responsiveness in the critically ill?