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Confounding by indication in retrospective studies of intracerebral hemorrhage: antiepileptic treatment and mortality.

ABSTRACT: Intracerebral hemorrhage (ICH) is a highly fatal disease with few proven treatments. Data to guide clinician decisions for therapies, including antiepileptic drugs (AED), are limited. Published studies on AED treatment in ICH have provided conflicting results. We investigated the effect of AED treatment on 90-day mortality after ICH in a large prospectively ascertained cohort.We conducted a retrospective analysis of a prospectively assembled cohort of patients with ICH in the supratentorial regions, comparing 90-day mortality and modified Rankin Score among 543 patients treated with AED during hospitalization and 639 AED-free ICH. Supratentorial ICH location was categorized as lobar or deep hemispheric.Multivariate analysis demonstrated an association between AED treatment and reduced 90-day mortality in supratentorial ICH (OR = 0.62, 95 % CI 0.42-0.90, p = 0.01) and the subset of lobar ICH (OR = 0.49, 95 % CI 0.25-0.96, p = 0.04). When analyses were restricted to subjects surviving longer than 5 days from ICH, however, no association between AED treatment and a 90-day outcome, regardless of hemorrhage location (all p > 0.15), was detected, despite more than adequate power to detect the originally observed association.These results suggest that AED treatment in acute ICH is not associated with 90-day mortality or outcome and that any detected association could arise by confounding by indication, in which the most severely affected patients are those in whom AEDs are prescribed. They provide a cautionary example of the limitations of drawing conclusions about treatment effects from observational data.

SUBMITTER: Battey TW

PROVIDER: S-EPMC3707622 | biostudies-literature | 2012 Dec

REPOSITORIES: biostudies-literature

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Confounding by indication in retrospective studies of intracerebral hemorrhage: antiepileptic treatment and mortality.

Battey Thomas W K TW Falcone Guido J GJ Ayres Alison M AM Schwab Kristin K Viswanathan Anand A McNamara Kristen A KA DiPucchio Zora Y ZY Greenberg Steven M SM Sheth Kevin N KN Goldstein Joshua N JN Rosand Jonathan J

Neurocritical care 20121201 3

<h4>Introduction</h4>Intracerebral hemorrhage (ICH) is a highly fatal disease with few proven treatments. Data to guide clinician decisions for therapies, including antiepileptic drugs (AED), are limited. Published studies on AED treatment in ICH have provided conflicting results. We investigated the effect of AED treatment on 90-day mortality after ICH in a large prospectively ascertained cohort.<h4>Methods</h4>We conducted a retrospective analysis of a prospectively assembled cohort of patient ...[more]

PMID: 22965324

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Project description:Numerous observational studies suggest that bisphosphonates reduce mortality. This study showed that bisphosphonate use is associated with lower mortality within days of treatment, although the association was not significant until the second week. Such an early association is consistent with confounding, although an early treatment effect cannot be ruled out.IntroductionThe purpose of this study was to examine whether confounding explains why numerous observational studies show that bisphosphonate use is associated with lower mortality. To this end, we examined how soon after treatment initiation a lower mortality rate can be observed. We hypothesized that, due to confounding, the association would be observed immediately.MethodsThis was a retrospective cohort study of hip fracture patients discharged from Swedish hospitals between 1 July 2006 and 31 December 2015. The data covered 260,574 hip fracture patients and were obtained from the Swedish Hip Fracture Register and national registers. Of the 260,574 patients, 49,765 met all eligibility criteria and 10,178 were pair matched (bisphosphonate users to controls) using time-dependent propensity scores. The matching variables were age, sex, diagnoses, prescription medications, type of hip fracture, type of surgical procedure, known or suspected dementia, and physical functioning status.ResultsOver a median follow-up of 2.8 years, 2922 of the 10,178 matched patients died. The mortality rate was 7.9 deaths per 100 person-years in bisphosphonate users and 9.4 deaths in controls, which corresponded to a 15% lower mortality rate in bisphosphonate users (hazard ratio 0.85, 95% confidence interval 0.79-0.91). The risk of death was lower in bisphosphonate users from day 6 of treatment, although the association was not significant until the second week.ConclusionBisphosphonate use was associated with lower mortality within days of treatment initiation. This finding is consistent with confounding, although an early treatment effect cannot be ruled out.

Project description:Background and purposeImpaired level of consciousness (LOC) on presentation at hospital admission in patients with intracerebral hemorrhage (ICH) may affect outcomes and the decision to withhold or withdraw life-sustaining treatment (WOLST).MethodsPatients with ICH were included across 121 Florida hospitals participating in the Florida Stroke Registry from 2010 to 2019. We studied the effect of LOC on presentation on in-hospital mortality (primary outcome), WOLST, ambulation status on discharge, hospital length of stay, and discharge disposition.ResultsAmong 37 613 cases with ICH (mean age 71, 46% women, 61% White, 20% Black, 15% Hispanic), 12 272 (33%) had impaired LOC at onset. Compared with cases with preserved LOC, patients with impaired LOC were older (72 versus 70 years), more women (49% versus 45%), more likely to have aphasia (38% versus 16%), had greater ICH score (3 versus 1), greater risk of WOLST (41% versus 18%), and had an increased in-hospital mortality (32% versus 12%). In the multivariable-logistic regression with generalized estimating equations accounting for basic demographics, comorbidities, ICH severity, hospital size and teaching status, impaired LOC was associated with greater mortality (odds ratio, 3.7 [95% CI, 3.1-4.3], P<0.0001) and less likely discharged home or to rehab (odds ratio, 0.3 [95% CI, 0.3-0.4], P<0.0001). WOLST significantly mediated the effect of impaired LOC on mortality (mediation effect, 190 [95% CI, 152-229], P<0.0001). Early WOLST (<2 days) occurred among 51% of patients. A reduction in early WOLST was observed in patients with impaired LOC after the 2015 American Heart Association/American Stroke Association ICH guidelines recommending aggressive treatment and against early do-not-resuscitate.ConclusionsIn this large multicenter stroke registry, a third of ICH cases presented with impaired LOC. Impaired LOC was associated with greater in-hospital mortality and worse disposition at discharge, largely influenced by early decision to withhold or WOLST.

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Confounding by indication in retrospective studies of intracerebral hemorrhage: antiepileptic treatment and mortality.

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Confounding by indication in retrospective studies of intracerebral hemorrhage: antiepileptic treatment and mortality.

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