Understanding the diagnostic process in a rare, genetic disease: a mixed methods study of schwannomatosis

Diagnostic errors are relatively common in medicine and can cause significant patient harm. We adapted the National Academy of Medicine’s model of the diagnostic process to examine diagnostic errors in schwannomatosis, a rare, genetic syndrome in which patients commonly develop multiple nerve sheath tumors and chronic pain. We specifically assessed how well the schwannomatosis diagnostic process currently functions; identified specific failures in the diagnostic process and assessed their contribution to diagnostic error; and explored the impact of diagnostic errors on patients’ lives. In study one, we reviewed the medical records of 97 schwannomatosis patients seen in two tertiary care clinics to assess the extent of diagnostic error in this population. It took a median of 7.9 years from patients’ first sign/symptom for a diagnosis of schwannomatosis to be established and communicated to patients. One-fifth of patients had a clear missed opportunity for appropriate workup that could have led to an earlier diagnosis. About one-third of patients experienced a misdiagnosis of their pain etiology, tumor pathology, or underlying genetic diagnosis. In study two, we created narrative summaries detailing patients’ diagnostic journeys using the medical record data of 52 schwannomatosis patients included in study one. Directed content analysis of these summaries identified the specific diagnostic process failures patients experience. Almost all patients experienced at least one failure, which most commonly reflected deficiencies in diagnostic testing, the clinical history/interview, or follow-up. Two-thirds of failures significantly impacted patient outcomes, most often by delaying needed diagnostic workup and communication of a final diagnosis to the patient. In study three, we interviewed 18 people with schwannomatosis from across the United States and used thematic analysis to explore patients’ symptom appraisal and the personal impact of diagnostic errors. Participants and their healthcare providers often ascribed schwannomatosis symptoms to more common conditions, which could delay care-seeking and initial workup. Diagnostic delay and misdiagnosis could result in unnecessary surgery, delayed receipt of effective pain management, psychological distress, and stigmatization. Collectively, these studies give unique insight into the prevalence, causes and ramifications of diagnostic error in schwannomatosis, and highlight opportunities to improve the diagnostic process across rare, genetic diseases