Risk of Shoulder Conditions After Vaccination: A Population-Based Study Using Real-World Data
Background:
Although shoulder conditions have been reported as an adverse event after intramuscular vaccination in the deltoid muscle, epidemiological data on shoulder conditions after vaccination are limited.
Aim:
Estimate the risk of shoulder pathologies after vaccination and evaluate possible risk factors.
Design:
Retrospective cohort study.
Adjustment:
Kaiser Permanente of Southern California, a large integrated healthcare organization.
Participants:
Kaiser Permanente Southern California members ages 3 and older who received an intramuscular vaccine administered into the deltoid muscle between April 1, 2016 and December 31, 2017.
Measurements:
A natural language processing (NLP) algorithm was used to identify potential shoulder conditions among vaccinated individuals with shoulder disorder diagnosis codes. All cases identified by NLP were manually confirmed in the chart based on our case definition. The characteristics of vaccinated people with and without shoulder conditions were compared.
Results:
Among 3,758,764 vaccines administered, 371 cases of shoulder disease were identified , with an estimated incidence of 0.99 (95% CI, 0.89 to 1.09) per 10,000 vaccines. The incidence was 1.22 (CI, 1.10 to 1.35) for the adult population (≥18 years) and 0.05 (CI, 0.02 to 0.14) for the pediatric population (3 to 17 years) vaccinated.
In the vaccinated adult population, older age, female sex, a greater number of outpatient visits in the 6 months before vaccination, a lower Charlson comorbidity index, and pneumococcal conjugate vaccine were associated with a higher risk of conditions of the shoulder.
Among influenza vaccines, quadrivalent vaccines were associated with an increased risk of shoulder conditions.
Simultaneous administration of vaccines was associated with an increased risk of shoulder conditions among older people.
Limitation:
Generalizability to other healthcare settings, use of administrative data, and residual confounding.
Conclusion:
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Primary funding source: (CDC) Centers for Disease Control and Prevention.
Comments
Shoulder injury, a rare potential side effect of vaccination
A retrospective cohort study found that shoulder injury occurred in fewer than 1 in 10,000 patients who received intramuscular vaccines administered into the deltoid muscle between April 2016 and December 2017 (pre-COVID-19 pandemic).
The authors say that given the high burden of shoulder conditions, doctors should pay attention to any factors that may further increase risks. While shoulder conditions can be prevented if caused by improper administration of the vaccine, their study did not determine the cause of shoulder injuries associated with the vaccine. The findings are published in Annals of Internal Medicine.
The National Vaccine Injury Compensation Program (VICP) provides financial compensation to those who suffered serious adverse events listed on its vaccine injury table.
In 2017, shoulder injury related to vaccine administration (SIRVA) was added to the vaccine injury table based on compelling evidence of a causal relationship between vaccine injection and deltoid bursitis .
In addition to bursitis, other shoulder conditions have been linked to vaccination. The proposed mechanism is that shoulder conditions are caused by immune responses when vaccines are injected into the shoulder joint, rather than the deltoid muscle. However, epidemiological data on shoulder conditions after vaccination are limited.
Researchers from the Kaiser Permanente Southern California Department of Research and Evaluation studied the health records of more than 3.7 million vaccinations administered during the study period to estimate the risk of shoulder conditions after vaccination and evaluate possible risk factor’s.
A natural language processing (NLP) algorithm was used to identify potential shoulder conditions among vaccinated individuals with shoulder disorder diagnosis codes and compared the characteristics of vaccinated individuals with and without shoulder conditions.
Among more than 3.7 million vaccines administered, 371 cases of shoulder pathology were identified, with an estimated incidence of 0.99 per 10,000 vaccinated adults. The incidence was even lower for pediatric recipients, with only 4 cases of shoulder conditions in more than 750,000 vaccinations.
The researchers also looked at risk factors for developing shoulder conditions and found that among adults, older age, female sex, a greater number of outpatient visits in the 6 months before vaccination, having fewer comorbidities, and receiving the vaccine conjugated antipneumococcal drugs were associated with an increased risk of shoulder conditions.
Among influenza vaccines, quadrivalent vaccines were associated with an increased risk of shoulder conditions.
Simultaneous administration of vaccines was associated with an increased risk of shoulder conditions among older people.
