2.1 Identification of patients with CRSwNP
The data was available from 1 January 2000 to 31 December 2019. The
study cohort included incident adult patients with a diagnosis of CRSwNP
between 1 January 2012 to 31 December 2018. The patients were identified
on their index date, the date of first CRSwNP diagnosis, by having any
of the following ICD-10 diagnosis codes: J32.4 or J33.0, J33.1, J33.8,
J33.9, or a polypectomy of internal nose reported by the Nordic
Classification of Surgical Procedures (NCSP) code DHB20. Patients with
cystic fibrosis (E84*) or ciliary dyskinesia (Q33*, Q34*) were excluded
from the study.
The patients were identified from the national Finnish Care Register for
Health Care (Hilmo) and Register of Primary Health Care (Avohilmo)
visits, from where their diagnoses, procedures, visits, and resource
utilization were extracted. The data from the Care Register for Health
Care was complemented with data from the Social Insurance Institution
(SII) for reimbursed medications and purchases, and with data from
Statistics Finland for vitality status and causes of death.
Data from 2000-2012 was used to assess comorbidities and clinical
characteristics. The baseline period was set to 36 months prior to
index, where baseline comorbidities and characteristics were described.
Patients were followed up until the end of the study (31 January 2019)
or death. Data for at least one year of follow-up was available for all
patients (Figure 1).