Validation of an algorithm to identify incident interstitial lung disease in patients with rheumatoid arthritis

Table 3 Frequency of specific ICD-9/10-CM ILD Codes using the final ILD case-finding algorithm

Table of diagnosis by ILD code
Diagnosis code and location of case qualifying^a ILD		Adjudicated ILD
Diagnosis code and location of case qualifying^a ILD		Yes, incident	Yes, prevalent	Not ILD	Total^b
515, Post inflammatory pulmonary fibrosis	HospitalPrimary	4	1	2	7
	HospitalNonPrimary	12	7	13	32
	OutpatientCT	33	9	8	50
	OutpatientHospital	4	2	1	7
516.31, Idiopathic pulmonary fibrosis	HospitalNonPrimary	1	0	0	1
516.31, Idiopathic pulmonary fibrosis	OutpatientCT	2	0	0	2
516.34, Respiratory bronchiolitis interstitial lung disease	OutpatientCT	0	1	0	1
516.34, Respiratory bronchiolitis interstitial lung disease	OutpatientHospital	0	0	1	1
516.8, Other specified alveolar and parietoalveolar pneumonopathies	HospitalPrimary	1	0	0	1
	HospitalNonPrimary	0	1	0	1
	OutpatientCT	1	2	0	3
714.81, Rheumatoid lung disease	HospitalPrimary	1	0	1	2
714.81, Rheumatoid lung disease	OutpatientCT	6	3	2	11
J84.10, Pulmonary fibrosis unspecified	HospitalNonPrimary	1	0	0	1
J84.112, Idiopathic pulmonary fibrosis	OutpatientCT	1	0	0	1
J84.9, Interstitial pulmonary disease, unspecified	HospitalNonPrimary	0	0	1	1
J84.9, Interstitial pulmonary disease, unspecified	OutpatientCT	2	1	0	3
M05.10, Rheumatoid lung disease	HospitalPrimary	0	1	0	1
Total		69	28	29	126

ILD interstitial lung disease
^a HospitalPrimary = inpatient primary diagnosis; HospitalNonPrimary = inpatient non-primary diagnosis; OutpatientCT = outpatient diagnosis preceded by CT within 90 days; and OutpatientHospital = outpatient diagnosis preceded by hospitalization within 90 days
^bThe count of each diagnosis code row in Table 3 may exceed the corresponding row counts in Supplemental Table 3, since Supplemental Table 3 shows the counts for all codes used to initially screen for ILD based on patients’ first ILD diagnosis appearing in the data. Table 3 reflects only ILD diagnosis codes included in the Final ILD algorithm, eliminating those that performed poorly. Patients commonly had multiple ILD diagnosis codes over time; those initially found in the data may be been re-categorized by the final algorithm. For example, if a patient’s first ILD diagnosis code was 491.9, then they would have been included in that count for Supplemental Table 3. However, in Table 3, this code was eliminated, so those patients would have been represented in Table 3 according to whatever their ILD diagnosis code was that appeared in the final ILD algorithm

ISSN: 1478-6362