Background: Large randomized and non-randomized trials in routine care are an important tool
to evaluate effectiveness and safety of medical interventions in clinical practice.
Complete assessment of serious adverse events (SAEs) is crucial to characterize the
safety profile of the drug or intervention under study. We linked data from a large
acupuncture trial with hospital claims data to evaluate the agreement of physician-reported
SAEs and SAEs identified by using hospital discharge diagnoses. Methods: Patients treated with acupuncture for chronic pain, asthma, allergic rhinitis, or
dysmenorrhea within the Acupuncture in Routine Care (ARC) studies were included in
this analysis. Patients eligible for ARC had to be insured with a large German statutory
health insurance (Techniker Krankenkasse; TK). Acupuncture treatment comprised of
a mean number of 10 acupuncture sessions within three months. Physician-reported SAEs
were assessed by a follow-up questionnaire. We used hospital claims data to identify
SAEs that led to hospitalisation. Cohen's Kappa was calculated as a measure of inter-observer
agreement between these two data sources. Results: A total of 42.272 patients (67.5% women, 32.5% men) treated by 6557 different physicians
were included in the analysis. Using hospital claims data, 566 patients with at least
one SAE during follow-up were identified. For 22 of them (3.9%), the physician also
reported a SAE. For 78 patients, only physician-based reporting, but not hospital
claims indicated occurrence of a SAE. The kappa for overall inter-observer agreement
was 0.06 (95% confidence interval 0.04 to 0.09). Conclusion: In this acupuncture trial, agreement between physician-reported SAEs and SAEs identified
via hospital discharge diagnoses was very low, most probably due to substantial SAE
underreporting by physicians. Especially in large trials in routine care, linkage
with secondary data sources may improve completeness and validity of data.
