Cohort
Anthony Kim MD, Heather Fullerton MD MAS, S. Claiborne Johnston MD PhDRisk of Vascular Events in Emergency Department Patients Discharged Home with Diagnosis of Dizziness or Vertigo
Annals of Emergency Medicine
January 2011; 34-41
- Submitted by:Drue Orwig - Emergency Medicine Resident Physician
- Institution:Grand Rapids Medical Education Partners, MSU College of Human Medicine
- Date submitted:3rd May 2011
1
Objectives and hypotheses
1.1
Are the objectives of the study clearly stated?
Yes the objective of the study was to evaluate a cohort of ED patients in California ERs whom were discharged home with a primary diagnosis of vertigo or dizziness to measure the risk of subsequent major vascular (cerebral or cardiovascular) events within a 180 day period. Secondary outcome was to time to first repeat ED visit for the same diagnosis, time to first cerebrovascular or cardiovascular event
2
Design
2.1
Is the study design suitable for the objectives?
Yes using a cohort study design the researchers were able to look at a large database of patients over a limited amount of time to evaluate for the chosen objectives.
2.2
Who / what was studied?
All ER patients aged 18 years or older in California who were discharged home with a primary diagnosis of vertigo or dizziness were studied from January 1 2005 to June 30 2005.
2.3
Was a control group used if appropriate?
There was no control group.
2.4
Were outcomes defined at the start of the study?
Yes both primary and secondary outcomes were defined in the introduction section.
2.5
Was this the right sample to answer the objectives?
Yes this was the right sample to answer the objective. However, they excluded all patients who were admitted with dizziness or vertigo as well as those who had a diagnosis or CVA or cardiovascular event and those who were transferred to another facility. This limits the patient population to those who appear to be low-risk and those who do not have an obvious source for the dizziness or vertigo. This makes the study results limited to only those individuals and not to all comers with dizziness or syncope.
2.6
Is the study large enough to achieve its objectives? Have sample size estimates been performed?
The population size was large (31,159 patients) but no sample size estimates were noted in the study.
2.7
Were all subjects accounted for?
Yes all subjects were accounted for however there was a chance, which was described in the article, that some patients initially evaluated in a California ER subsequently went to an ER outside of the California system and therefore would not be accounted for. They did try to limit this by only including patients who were residents of California.
2.8
Were all appropriate outcomes considered?
No other causes for vertigo/dizziness that may have been missed on initial ED evaluation and lead to long-term morbidity and mortality were not included such as subarachnoid hemorrhage.
2.9
Has ethical approval been obtained if appropriate?
Approval was obtained from both the California Health and Human Services Agency's Committee for the Protection of Human Subjects and the local institutional review board.
3
Measurement and observation
3.1
Is it clear what was measured, how it was measured and what the outcomes were?
Yes the primary and secondary outcomes were measured using survey analysis. They then constructed hazard plots as well as univariable and multivariable Cox models
3.2
Was the assessment of outcomes blinded?
No it was not blinded.
3.3
Was follow up sufficiently long and complete?
Follow-up was within 180 days which seems sufficient. Follow-up was complete except for those patients that may have been seen initially at a California ER and then subsequently went to an ER out-of-state and could not be followed.
3.4
Are the measurements valid?
Yes the results are valid by using survival analysis techniques, hazard plots, and univariable and multivariable Cox models
3.5
Are the measurements reliable?
Yes the measurements appear to be reliable however they differ from previous studies estimating short-term prognosis of patients with dizziness or vertigo so the results should be validated with subsequent studies.
3.6
Are the measurements reproducible?
Yes the measurements should be reproducible in different studies.
4
Presentation of results
4.1
Are the basic data adequately described?
Yes the basic data are described adequately except that due to the fact that this is a cohort study, some data is unavailable or not described such as other co-morbidities and previous history of dizziness or vertigo.
4.2
Are the results presented clearly, objectively and in sufficient detail to enable readers to make their own judgement?
The results are presented clearly and in sufficient detail. I do not think the explanation regarding the increased incidence of cerebrovascular events in the first 30 days after the initial ER visit is accurate and is presumptive. There appears to be a significant (30.2 events/10,000 persons vs 6.5 events/10,000 persons) increased risk of cerebrovascular event during the first month time period that cannot be attributed solely to a "temporal association with the ED visit" as they suggest and should be evaluated further.
4.3
How large are the effects within a specified time?
0.93% risk for all major vascular events in the 180-day period
4.4
Are the results internally consistent, i.e. do the numbers add up properly?
Yes the numbers add up correctly.
5
Analysis
5.1
Are the data suitable for analysis?
Yes the data are suitable for analysis.
5.2
Are the methods appropriate to the data?
Yes the methods are appropriate to the data
5.3
Are any statistics correctly performed and interpreted?
No, I do not feel the statistics regarding the increased incidence of cerebrovascular events in the first 30 days after ED visit are accurately interpreted. Otherwise the rest of the statistics are correct.
6
Discussion
6.1
Are the results discussed in relation to existing knowledge on the subject and study objectives?
Yes the results of the study were compared to two previous studies evaluating short-term prognosis for patients diagnosed with vertigo or dizziness.
6.2
Is the discussion biased?
The discussion is objective in evaluating the results except for the portion regarding the cerebrovascular events.
7
Interpretation
7.1
Are the author's conclusions justified by the data?
Yes the conclusions are justified and consistent with the data.
7.2
What level of evidence has this paper presented? (using CEBM levels)
2b
7.3
Does this paper help me to answer my problem?
Yes it helps to feel more confident sending patients home with dizziness or vertigo knowing that there is a low-likelihood of a bad short-term outcome. The next research regarding this topic should include clinical prediction methods to select those patients who are at a greater risk for major vascular event with symptoms of vertigo or dizziness.
8
Implementation
8.1
Can any necessary change be implemented in practice?
The high prevalence of these presentations and the incentives to pursue costly evaluations to best exclude these infrequent complications continues to highlight the utility of developing reliable methods to stratify risk through the development of clinical prediction rules and more reliable and highly accurate bedside examination techniques.
8.2
What aids to implementation exist?
N/A
8.3
What barriers to implementation exist?
The lack of specific risk factors that help determine a patients overall risk for major adverse event in the short-term time period.
8.4
Are the study patients similar to your own?
Yes they are similar
8.5
Does the paper give any conclusions that will affect what you will offer or tell your patient?
I will feel more confident discharging a patient home with dizziness or vertigo without a specific identifiable source and will feel more confident discussing with my patients the low likelihood of a negative outcome if they cause for the symptom was not found on evaluation.