Sociodemographic Variations in Reporting Rates of Adverse Reactions to Drugs

Adverse reactions to drugs are common and a leading cause of morbidity and mortality.[1] However, because many drug reactions are not reported to the Food and Drug Administration (FDA), drug safety information may not adequately represent the adverse events that patients experience. Researchers estimate that over 90% of adverse drug reactions worldwide, including many serious and severe reactions, are not reported.[2] This may be because many clinicians and patients mistakenly believe that once drugs are approved, their adverse events are well-documented, no additional reporting is necessary or only drugs that are well-tolerated are marketed.[3],[4] Other barriers to submitting adverse event reports include a lack of awareness of reporting systems, language difficulties and time constraints.

A study published in Drug Safety in 2024 found that sociodemographic factors, such as living in a county with higher percentages of African American, American Indian or Alaska Native residents; higher rates of lack of access to health care; low English proficiency; and lower household income, contribute to lower rates of adverse event reporting.[5] Because these groups may already be at a higher risk of experiencing adverse reactions to drugs than the population as a whole, failure to capture this information in adverse event reporting systems may exacerbate health disparities.

Overview of adverse events and adverse event reporting

The FDA usually approves a drug after clinical trials have demonstrated that the medication is safe and effective and that its benefits outweigh its risks.[6] All drugs, however, have adverse events, which the agency describes as “unwanted undesirable effects that are possibly related to a drug.” These undesirable effects can range from mild (such as a runny nose) to severe (such as liver damage or heart attacks) and can lead to hospitalization, permanent organ damage and even death. Although many adverse events are common, uncommon and rare reactions occur as well.

Clinical trials are often conducted with a relatively small number of subjects over a limited time period. Many adverse effects associated with a drug are first detected after approval.[7] Moreover, subjects in trials to support drug approval are often carefully selected. Subjects may be less diverse and have fewer risk factors for adverse events — such as older age, comorbidities (having two or more health conditions at the same time) or concomitant drug use — than people who are excluded from the trials. Thus, the subjects may not be representative of the larger population of people who may be exposed to a drug after approval.

For drugs that are already on the market, the FDA relies on postmarketing adverse event reports that are collected through the FDA Adverse Event Reporting System (FAERS).[8] These reports are a key source for detecting new or rare safety concerns and enable the agency to reassess a drug’s benefit-risk ratio and, if necessary, require updates in the prescribing information. In the United States, the public (including patients and clinicians) can report adverse events either directly to the FDA’s MedWatch program or by contacting drug manufacturers, who are required to submit these reports to the FDA. Reports from patients are especially valuable because they tend to provide detailed information, such as how the drug reaction effected patients’ social or work life.[9]

The new study

The FAERS database contains about 28 million reports covering 1996 to mid-2024.[10] The majority of reports are submitted by drug manufacturers; only about 5% of all reports are directly submitted to the FDA by consumers (such as patients and caregivers) and health care professionals. For the new study, the researchers, some of whom are FDA officials, analyzed the direct consumer reports that were submitted to the FDA between January 2011 and December 2015.

Although the FAERS database generally does not include information about where the person who experienced the adverse event lives, about 30% of all direct consumer reports contained address data that allowed the researchers to match most of these reports to specific U.S. counties. The researchers then estimated the reporting rate per 100,000 residents for each U.S. county and used other data sources, such as Census data, that enabled them to associate specific reports with county-level information such as age, sex, race, English proficiency and household income.

The researchers found that the rates of direct consumer reporting of adverse events varied substantially across U.S. counties.[11] For instance, the counties with the highest reporting rates had more than 18 reports per 100,000 residents, whereas counties with the lowest reporting rates had six or fewer reports per 100,000 residents. For 19.5% of the 3,136 U.S. counties, the study methods did not allow the researchers to identify any direct consumer reports submitted to FAERS during the five-year study period.

The study identified sociodemographic factors that may explain some of the variation in the rates of adverse event reporting. For example, even after adjusting for use of prescription drugs, reporting was higher in counties with a higher percentage of residents who were older than 65 years of age or female. Lower reporting rates were associated with counties that had a higher proportion of African Americans, American Indians or Alaska Natives per 100,000 residents, whereas higher reporting rates were found in counties that had a higher proportion of Whites. Lower reporting rates were also more common in counties with a higher proportion of residents with low English proficiency, lower household incomes, living in rural areas and with less access to primary care and mental health care professionals.

The study was limited to direct consumer reports and did not account for adverse event reports for drugs that were purchased over the counter, via mail order or that were administered to hospitalized patients. Moreover, the approximately 95% of reports that pharmaceutical manufacturers send to the FDA were excluded. Nonetheless, the study found substantial variations in rates of consumer reporting of adverse reactions to drugs that were associated with sociodemographic factors and health care access. To monitor and improve the safety of medicines across the entire population, the study indicates that more representative data on drug-related adverse events are needed.[12]

What You Can Do

Especially when starting or discontinuing a drug or changing your dose, be on the lookout for adverse drug reactions.[13] Talk to your clinician or pharmacist about possible adverse events, particularly if you are already taking other drugs or have an underlying condition that makes you more vulnerable.

If you are experiencing an adverse reaction to a drug, tell your clinician and discuss whether there are ways you can reduce your risks, such as adjusting the dose or switching to a different medication. Adverse events can be reported to FDA’s MedWatch program at www.fda.gov/MedWatch or by calling 800-332-1088.
 

References

[1] Inácio P, Gomes JJ, Airaksinen M, et al. Exploring sociodemographic and economic factors that promote adverse drug reactions reporting by patients. Health Policy. 2018;122(3):263-268.

[2] Hazell L, Shakir SA. Under-reporting of adverse drug reactions: a systematic review. Drug Saf. 2006;29(5):385-396.

[3] García-Abeijon P, Costa C, Taracido M, et al. Factors associated with underreporting of adverse drug reactions by health care professionals: a systematic review update. Drug Saf. 2023;46(7):625-636.

[4] Costa C, Abeijon P, Rodrigues DA, et al. Factors associated with underreporting of adverse drug reactions by patients: a systematic review. Int J Clin Pharm. 2023;45(6):1349-1358.

[5] Muñoz MA, Dal Pan GJ, Wei YJ, et al. Sociodemographic characteristics of adverse event reporting in the USA: An ecologic study. Drug Saf. 2024;47(4):377-387.

[6] Food and Drug Administration. Finding and learning about side effects (adverse reactions). August 8, 2022. https://www.fda.gov/drugs/information-consumers-and-patients-drugs/finding-and-learning-about-side-effects-adverse-reactions. Accessed May 3, 2024.

[7] Muñoz MA, Dal Pan GJ, Wei YJ, et al. Sociodemographic characteristics of adverse event reporting in the USA: An ecologic study. Drug Saf. 2024;47(4):377-387.

[8] Food and Drug Administration. Sociodemographic characteristics of adverse event reporting. March 1, 2024. https://www.fda.gov/drugs/spotlight-cder-science/sociodemographic-characteristics-adverse-event-reporting?utm_medium=email&utm_source=govdelivery. Accessed May 3, 2024.

[9] Inácio P, Gomes JJ, Airaksinen M, et al. Exploring sociodemographic and economic factors that promote adverse drug reactions reporting by patients. Health Policy. 2018;122(3):263-268.

[10] Food and Drug Administration. FDA adverse Avent Reporting System (FAERS) public dashboard. December 7, 2023. https://www.fda.gov/drugs/questions-and-answers-fdas-adverse-event-reporting-system-faers/fda-adverse-event-reporting-system-faers-public-dashboard. Accessed March 6, 2024.

[11] Food and Drug Administration. Sociodemographic characteristics of adverse event reporting. March 1, 2024. https://www.fda.gov/drugs/spotlight-cder-science/sociodemographic-characteristics-adverse-event-reporting?utm_medium=email&utm_source=govdelivery. Accessed May 3, 2024.

[12] Food and Drug Administration. Sociodemographic characteristics of adverse event reporting. March 1, 2024. https://www.fda.gov/drugs/spotlight-cder-science/sociodemographic-characteristics-adverse-event-reporting?utm_medium=email&utm_source=govdelivery. Accessed May 3, 2024.

[13] Food and Drug Administration. Finding and learning about side effects (adverse reactions). August 8, 2022. https://www.fda.gov/drugs/information-consumers-and-patients-drugs/finding-and-learning-about-side-effects-adverse-reactions. Accessed May 3, 2024.