ObjectiveTraditional neurology teaching states that when mean arterial pressure dips below a 60 mm Hg threshold, there is an increase in stroke risk due to cerebral hypoperfusion. The aim of this study was to determine whether intensive lowering of systolic blood pressure increases adverse cardiovascular outcomes by examining the association between achieved blood pressure values, specifically mean arterial pressure and pulse pressure, and risk of stroke.MethodsData from participants in the Systolic Blood Pressure Intervention Trial (SPRINT) and the Action to Control Cardiovascular Risk in Diabetes (ACCORD) Blood Pressure (BP) trial were examined, using survival analysis to model minimal arterial pressure and average pulse pressure during the study period against risk of stroke, hypotension, and syncope, with death as a competing risk.ResultsIn both SPRINT and ACCORD participants, there was no increase in stroke risk with achieved mean arterial pressure values below 60 mm Hg. In SPRINT participants, achieved mean arterial pressure values greater than 90 mm Hg were associated with a 247% (HR: 3.47, 95% CI: 2.06–5.85) higher risk of stroke compared with participants in the 80–89 mmHg reference group. No association was found between low achieved pulse pressure values and greater stroke risk in either the SPRINT or ACCORD participants, as well as no association between mean arterial pressure and pulse pressure values and risk of syncope.InterpretationIntensive lowering of systolic blood pressure does not increase risk of stroke in hypertensive patients, despite extremely low mean arterial pressure or pulse pressure values.
To the Editor In their study examining rates of persistent postconcussive symptoms (PPCS) in children and adolescents with early vs later return to physical activity, Dr Grool and colleagues found that PPCS occurred in 30.4% of all participants. 1 Although their main finding that PPCS was observed less frequently in participants who began activity within 7 days after acute concussion compared with those who abstained during the same period (28.7% vs 40.1%) provides the groundwork for continued study into the effects and timing of physical activity during recovery from concussion, the high rate of PPCS in the study population should also be highlighted.Rates of PPCS are traditionally thought to range between 5% and 10%. A commonly cited study of collegiate football players found that 91% of athletes fully recovered to baseline symptom levels within 7 days and showed no evidence of lingering impairments of memory, cognitive processing, or mental flexibility 90 days after concussion. 2 Other studies examining adult populations found approximately 15% of concussion patients experienced PPCS 3 months after injury. 3 Given that another study 4 has shown similar rates of PPCS in children and adolescents as reported by Grool and colleagues, it may be time to revisit the notion that most individuals recover fully and rapidly following concussion. In spite of a newer study indicating the proportion of adult concussion patients experiencing PPCS 1 month after injury may exceed 50%, 5 it appears the field is still anchored to the lower estimated range. Although valid concerns can be raised about potential false-positive PPCS diagnoses, 5 the potential magnitude by which these cases have been underestimated warrants reassessment.Better understanding of the number of patients with PPCS has implications for lost time from work, play, or school; quality of care; and clinical resource allocation. An increase in the number of patients experiencing PPCS will require more clinicians to provide care. A complete understanding of PPCS rates will also enable health systems to ensure that appropriate resources are allocated to best meet patient needs, help manage expectations of outcomes, and better inform patient education (the only class I evidence for concussion treatment).
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