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.

Input: Consider Input: Context: To test whether subsensory vibratory noise applied to the sole of the foot using a novel piezoelectric vibratory insole can significantly improve sensation, enhance balance, and reduce gait variability in elderly people, as well as to determine the optimal level of vibratory noise and whether the therapeutic effect would endure and the user's sensory threshold would remain constant during the course of a day.", 'A randomized, single-blind, crossover study of 3 subsensory noise stimulation levels on 3 days.', 'Balance and gait laboratory.', 'Healthy community-dwelling elderly volunteers (N=12; age, 65-90y) who could feel the maximum insole vibration.', 'A urethane foam insole with the piezoelectric actuators delivering subsensory vibratory noise stimulation to the soles of the feet.', 'Balance, gait, and timed Up and Go (TUG) test.', 'The vibratory insoles significantly improved performance on the TUG test, reduced the area of postural sway, and reduced the temporal variability of walking at both 70% and 85% of the sensory threshold and during the course of a day. Vibratory sensation thresholds remained relatively stable within and across study days.
Answer: This study provides proof of concept that the application of the principle of stochastic resonance to the foot sole sensory system using a new low-voltage piezoelectric technology can improve measures of balance and gait that are associated with falls. Effective vibratory noise amplitudes range from 70% to 85% of the sensory threshold and can be set once daily.

Output: Does a shoe insole delivering subsensory vibratory noise improve balance and gait in healthy elderly people?

Input: Consider Input: Context: There is a strong association between migraine and depression. The aim of this study is to identify migraine-specific factors involved in this association.', 'We conducted a cross-sectional study in a large, well-defined cohort of migraine patients (n=2533). We assessed lifetime depression using validated questionnaires, and diagnosed migraine based on the International Classification of Headache Disorders III-beta criteria. Multivariate regression analyses were conducted.', 'Of the 2533 migraineurs that were eligible, 1137 (45%) suffered from lifetime depression. The following independent factors were associated with an increased depression prevalence: i) migraine-specific risk factors: high migraine attack frequency and the presence of allodynia, ii) general factors: being a bad sleeper, female gender, high BMI, being single, smoking, and a low alcohol consumption.
Answer: This study identified allodynia, in addition to high migraine attack frequency, as a new migraine-specific factor associated with depression.

Output: Is allodynia associated with a higher prevalence of depression in migraine patients?

Input: Consider Input: Context: Hyponatremia has been shown to predict adverse outcome in congestive heart failure and pneumonia among other common clinical entities, but its significance in the general population is elusive.', 'The population-based Copenhagen Holter Study included 671 men and women aged 55 to 75 years with no history of cardiovascular disease, stroke, or cancer. Baseline evaluation included 48-hour ambulatory electrocardiogram monitoring, blood tests, and a questionnaire. Hyponatremia was defined as s-Na < or = 134 mEq/L or s-Na < or = 137 mEq/L according to previously accepted definitions. An adverse outcome was defined as deaths or myocardial infarction. Median follow-up was 6.3 years.', 'Fourteen subjects (2.1%, group A) had s-Na < or = 134 mEq/L, and 62 subjects (9.2%, group B) had s-Na < or = 137 mEq/L. No subject had s-Na < 129 mEq/L. An adverse outcome occurred in 43% of group A, 27% of group B, and 14% of subjects with s-Na >137 mEq/L (controls) (P < .002). Adjusted hazard ratio for adverse outcome was 3.56 (95% confidence interval [CI], 1.53-8.28, P < .005) in group A compared with controls and 2.21 (95% CI, 1.29-3.80, P < .005) in group B after controlling for age, gender, smoking, diabetes, low-density lipoprotein cholesterol, and blood pressure. The hazard ratios were robust for additional adjusting for variables showing univariate association to hyponatremia (ie, beta-blocker and diuretic use, heart rate variability, creatinine, C-reactive protein, and NT-pro brain natriuretic peptide). By excluding diuretic users (18% of subjects), the adjusted hazard ratio for adverse outcome was 8.00 (95% CI, 3.04-21.0, P < .0001) in group A and 3.17 (95% CI, 1.76-5.72, P = .0001) in group B compared with controls.
Answer: Hyponatremia is an independent predictor of deaths and myocardial infarction in middle-aged and elderly community subjects.
Output: Does mild hyponatremia carry a poor prognosis in community subjects?