JAMA : the journal of the American Medical Association
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Randomized Controlled Trial Multicenter Study
Testosterone Treatment and Cognitive Function in Older Men With Low Testosterone and Age-Associated Memory Impairment.
Most cognitive functions decline with age. Prior studies suggest that testosterone treatment may improve these functions. ⋯ Among older men with low testosterone and age-associated memory impairment, treatment with testosterone for 1 year compared with placebo was not associated with improved memory or other cognitive functions.
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Randomized Controlled Trial Multicenter Study Pragmatic Clinical Trial
Effect of Collaborative Care vs Usual Care on Depressive Symptoms in Older Adults With Subthreshold Depression: The CASPER Randomized Clinical Trial.
There is little evidence to guide management of depressive symptoms in older people. ⋯ Among older adults with subthreshold depression, collaborative care compared with usual care resulted in a statistically significant difference in depressive symptoms at 4-month follow-up, of uncertain clinical importance. Although differences persisted through 12 months, findings are limited by attrition, and further research is needed to assess longer-term efficacy.
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Observational studies almost always have bias because prognostic factors are unequally distributed between patients exposed or not exposed to an intervention. The standard approach to dealing with this problem is adjusted or stratified analysis. Its principle is to use measurement of risk factors to create prognostically homogeneous groups and to combine effect estimates across groups. ⋯ A second approach, instrumental variable analysis, relies on identifying a variable associated with the likelihood of receiving the intervention but not associated with any prognostic factor or with the outcome (other than through the intervention); this could mimic randomization. However, as with assumptions of other adjustment approaches, it is never certain if an instrumental variable analysis eliminates bias. Although all these approaches can reduce the risk of bias in observational studies, none replace the balance of both known and unknown prognostic factors offered by randomization.