Abstract
BACKGROUND: Early diagnosis in progressive supranuclear palsy (PSP) and corticobasal syndrome (CBS) is important for clinical care and key to developing successful disease-modifying agents. The patient-dependent phases of decision-making made before contact with a healthcare professional have been inadequately studied. OBJECTIVES: To evaluate the patient-dependent phases of decision-making from symptom onset, comparing this to clinician and/or health system delays within the overall diagnostic pathway. METHODS: Using the Anderson General Model of Total Patient Delay and a mixed-methods approach in participants with PSP/CBS and their caregivers recruited to the Scottish PSP and CBS cohort, we quantified and evaluated the determinants of "appraisal", "illness," and "behavioral" delay, comparing this to the clinician and/or health system delays ("treatment" delay) within the overall time from symptom onset to diagnosis. RESULTS: The time from index symptom onset to diagnosis was 3.26 (interquartile range [IQR] = 2.42, 4.75) years in PSP and 2.58 (IQR = 1.69, 4.08) years in CBS. Patient appraisal delay was 24 (IQR = 6, 60) weeks in PSP and 8 (IQR = 5, 24) weeks in CBS, illness delay 0 (IQR = -14, 0) weeks in PSP and 0 (IQR = -4, 0) weeks in CBS, with little perceived behavioral delay. Determinants of delay included the non-specificity of symptoms, normalization of symptoms within the context of age or normal physiological variability, and the extent of insight into new somatic symptoms. CONCLUSIONS: Although patient appraisal delay contributes to overall diagnostic delay in PSP/CBS, the greater proportion of overall diagnostic delay arises after contact with a healthcare professional (treatment delay).