HSR&D Home » Research » RRP 11-267 – HSR&D Study
Blood Pressure Management in the Year after a Stroke
Eric Cheng, MD MS
VA Greater Los Angeles Healthcare System, West Los Angeles, CA
West Los Angeles, CA
Funding Period: April 2012 - September 2013
Stroke is the leading cause of adult acquired disability in the United States. Having a stroke is the most powerful predictor for having a recurrent stroke. Therefore, patients who develop a stroke should have their modifiable risk factors managed aggressively, especially the premier risk factor of elevated blood pressure (BP).
Studies in the general population show that BP control is not optimal. However, among patients with a recent stroke, there is a unique opportunity to achieve better BP control. Although patients with an acute stroke may have elevated BP values and require further BP management, the experience of having a recent stroke may be a "teachable moment." Patients may be highly motivated to lower their BP because the symptoms of stroke are tangible. However, it is not known whether clinicians and patients capitalize on this moment by making changes in medication prescribing and medication adherence behavior during this limited window of opportunity.
In this Rapid Response Proposal (RRP), we leveraged data already collected in a chart review conducted by OQP/PCS/stroke QUERI and supplementing it with VA administrative data consisting of outpatient BP and medication data on the same cohort of veterans, then merging the datasets to better understand post-discharge management of BP for persons with a recent stroke. The specific aims are:
1)To measure treatment intensification and its impact on BP values one year after a stroke. Our hypothesis is that treatment intensification is associated with improved BP values, but that it occurs in less than half of all patients.
2)To measure patient medication adherence and its impact on BP values one year after a stroke. Our hypothesis is that patient adherence is associated with improved BP values, but that patient adherence in the year after discharge is not different from patient adherence in the year prior to admission.
This is a retrospective cohort study of veterans hospitalized with an acute ischemic stroke. The objective was to measure treatment intensification and medication adherence in the year after a stroke and determine its relationship to BP control at one year. The index date is the date of hospital admission for stroke. We used BP and medication data in the year prior to admission for calculating baseline BP, treatment adherence, and medication adherence levels.
The VA Office of Quality and Performance (OQP), Patient Care Services (PCS), and the stroke QUERI collaborated to conduct the Office of Quality and Performance Stroke Special Study. It was a retrospective cohort of 5000 veterans admitted to all Veterans Affairs Medical Centers in FY 2007 with a primary discharge diagnosis of ischemic stroke.
We merged the OQP cohort with 3 sets of administrative datasets:
1)The Corporate Data Warehouse (CDW) contains all vital sign data taken from VISTA back to 1999. It is updated daily.
2)The Pharmacy Benefits Management (PBM) contains data about outpatient pharmacy medications starting from FY1999. It is updated monthly.
3)Austin Information Technology Center (AITC) contains inpatient and outpatient data of visit dates, provider specialty, and diagnosis and procedural codes. It also includes date of death from the vital signs field.
We assembled a national cohort of 3987 Veterans admitted to a any of the 130 Veterans Administration (VA) Medical Centers in fiscal year 2007 with a diagnosis of acute ischemic stroke and who had visits to VA primary care clinics in the year prior to and in the year after the hospitalization for stroke. From administrative databases, we obtained BP values and prescribed BP medications in the year before and after index stroke hospitalization. Medication adherence was assessed by calculating the mean medication possession ratio among individual BP medications. We identified opportunities for treatment intensification if a Veteran had a systolic BP value 160 mm Hg (Stage 2 hypertension). We defined treatment intensification as any BP medication dose increase or addition of a new BP medication within 30 days of the intensification opportunity. We excused providers from intensification if there was a recent intensification in the past 30 days or if there is a scheduled visit in the next 14 days. We used paired t-tests to compare changes across the two years.
We identified 2832 Veterans with pre and post-stroke data. There were significant improvements in the mean systolic BP (136 mm lowered to 129 mm Hg, p<0.0001) and the proportion of patients with controlled BP (70% to 83%, p<0.00001). The adherence was high and unchanged when measured as the medication possession ratio (88% versus 87%, p=0.93). However, when the medication possession ratio was dichotomized at 80%, we did see an improvement (73% to 79%, p<0,00001). Despite the overall improvement in blood pressure, we saw that among 640 opportunities to intensify blood pressure, it was only performed 193 times (30%).
We are performing sensitivity analyses to determine whether we get the same results for Stage 1 Hypertension (140/90) as we did for Stage 2 Hypertension (160/100)
Back to the specific aims, we determined that:
1) Most stroke patients had adequate BP control. However, among patients who did not acheive BP control, there were oppotunities to intensify their medication regimen, but it did not happen.
2) Medication adherence was very high and unchanged in the year before and after stroke. Therefore, the barrier to BP control appears to be lack of treatment intensificaiton instead of lack of medication adherence.
These results indicate that while BP control improves in the post-stroke period, there remain a considerable number of opportunities when intensification did not occur.
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DRA: Cardiovascular Disease
DRE: Prognosis, Treatment - Comparative Effectiveness
MeSH Terms: none