5. Limitations
It is important to acknowledge the limitations of this study. First, the major is the underreporting of AEs by healthcare professionals, leading to incomplete data and an inaccurate representation of the true safety profile of drug. Second, the quality of data in pharmacovigilance databases can vary and hinder the analysis and interpretation of safety signals. Third, pharmacovigilance data often lacks comprehensive information about confounding factors that could contribute to AEs. Therefore, it is important to consider these limitations when interpreting pharmacovigilance data, as well as making decisions regarding drug and risk management. However, this study identified signals, such as hemiplegic migraine, asthenia, constipation, and flatulence, that are previously unknown or underestimated risk associated with pirfenidone or nintedanib, and provides an opportunity to assess ADRs that may not be detected during pre-approval clinical trials, which typically involve a limited number of patients.