vaccine gettyimages-1884958713-612x612.jpgData analysis uncovers variability in vaccine safety results across algorithms

Different case identification algorithms can significantly impact the reported incidence rates of outcomes related to pneumococcal vaccine safety.


Domain(s)
: maternal-child health, CV-diabetes


Summary

Background
Large health insurance claims databases can be leveraged to estimate rates of rare safety outcomes using algorithms consisting of diagnosis, procedure, and medication codes. These algorithms are subject to error. Using two algorithms for each outcome, we measured rates of rare outcomes that could be used to contextualize adverse events among people receiving pneumococcal vaccines in clinical trials or clinical practice. We also assessed the influence of algorithm choice on the rates of the outcomes. 


Methods
We used closed administrative medical and pharmacy claims in the Healthcare Integrated Research Database (HIRD®) to construct a broad cohort of individuals less than 100 years old (i.e., the target cohort) and a trial-similar cohort of individuals resembling those potentially eligible for a vaccine clinical trial. We stratified by age and sex and used specific and sensitive algorithms to estimate rates of 39 outcomes including cardiac/cerebrovascular, metabolic, allergic/autoimmune, neurological, and hematologic outcomes. Specific algorithms intended to reduce false positive errors, while sensitive algorithms intended to reduce false negative errors, thereby providing lower and upper bounds for the "true" rates. 


Results
We followed approximately 40 million individuals in the target cohort for an average of 3 years. Of 39 outcomes, 14 (36%) had a rate from the specific algorithm that was less than half the rate from the sensitive algorithm. Rates of cardiac/cerebrovascular outcomes were most consistent (average ratio of rates from specific algorithms compared to rates from sensitive algorithms = 0.76). For example, the estimated rate of thrombotic disorders was 456.3 cases per 100,000 person-years based on the specific algorithm versus 490.9 cases per 100,000 person-years based on the sensitive algorithm (Table 1). In contract, the rates of neurological and hematologic outcomes were the least consistent (average ratio of rates = 0.33 and 0.36, respectively). 

Table 1. Incidence rates of cardiac and cerebrovascular outcomes in the target cohort, by sensitive and specific algorithms.

Outcome

Target cohort

Sensitive algorithm

Specific algorithm

Rate from specific algorithm / rate from sensitive algorithm

Rate per 100,000 person-years

95% CI

95% CI

Rate per 100,000 person-years

95% CI

95% CI

Lower

Upper

Lower

Upper

All cohort members

39,919,149

39,919,149

Cardiac and cerebrovascular outcomes

Acute myocardial infarction

228.1

227.3

229.0

192.2

191.4

193.0

0.84

Cardiomyopathies and acute cardiac
     inflammation

200.4

199.6

201.2

174.3

173.6

175.1

0.87

Conduction disorders and arrhythmias

895.2

893.4

896.9

741.0

739.4

742.6

0.83

Coronary artery disease and angina

643.9

642.5

645.4

585.4

584.0

586.9

0.91

Heart failure

420.5

419.3

421.7

350.2

349.1

351.3

0.83

Kawasaki disease

2.1

2.1

2.2

0.1

0.1

0.2

0.05

Stroke

212.6

211.8

213.5

189.8

189.1

190.6

0.89

Transient ischemic event

230.9

230.0

231.8

168.6

167.8

169.3

0.73

Thrombotic disorders, including venous
     thromboembolism

490.9

489.7

492.2

456.3

455.0

457.5

0.93

Abbreviations: CI=confidence interval

Figure 1. Ratios of rates estimated from specific algorithms compared to rats estimated from sensitive algorithms in the target cohort. For each category of outcomes (cardiovascular/cerebrovascular, metabolic, allergic/autoimmune, neurological, and hematologic), the overall ratio indicated by black bars is the mean of the ratios for all outcomes in the category.


Vaccine Safety.png

Abbreviations: CIDP = chronic inflammatory demyelinating polyradiculoneuropathy

Rate ratios closer to 1 indicate the algorithms produced similar rates of the outcome, and thus indicate less variation between the specific and sensitive algorithms. Rate ratios closer to 0 indicate greater variation between the two algorithms and very different outcome rates. 

Key takeaways

  • Using multiple algorithms to ascertain outcomes in claims data can be informative about the extent of uncertainty due to outcome misclassification.
  • Cardiac and cerebrovascular outcome rates were similar regardless of the algorithm.
  • For other outcomes, rates varied substantially by algorithm.
  • Further validation studies will be needed to assess accuracy of the algorithms.
  • This study provides guidance for addressing outcome misclassification for studies of pneumococcal vaccines and other safety outcomes using administrative data in the absence of validated algorithms.

 
Publications

  • Crowe CL, Dreyfus J, Lanes S, Chung H, Watson W. Variation in incidence rates of outcomes relevant to vaccine safety monitoring in a US commercially insured population by case identification algorighm. Vaccine. 2024 Jul 11;42(18):3811-3813. doi: 10.1016/j.vaccine.2024.04.095. Epub 2024 May 6. PMID: 38714442. https://pubmed.ncbi.nlm.nih.gov/38714442/


Carelon Research project team: Christopher L. Crowe, Stephan Lanes, Haechung Chug
*Carelon Research associate at the time of the study.


For more information on a specific study or to connect with the Actionable Insights Committee,
contact us at [email protected].

Sponsor:  Funded by Pfizer.

Dissemination and sharing of the Newsletter is limited to Elevance Health and its subsidiaries, and included findings and implications are for Elevance Health and its affiliates’ internal use only.



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