TABLE 3.

Features Used in Each of the Models

Outcome Modeled	Feature	Data Type	Time Window
Pneumonitis 1y	Rel freq of C34, C78, R91, J, R05, R06, R07, R09 codesa	ICD-10 condition codes	1 year
	Rel freq of C34 code	ICD-10 condition codes
	Rel freq of C78 code	ICD-10 condition codes
	OH of J44 code indicator	ICD-10 condition codes
	OH of smoking indicator	Curation	Smoking history
	OH of smoking indicator and OH (C34 or C78 codes) indicator interaction	Curation and ICD-10 condition codes	Smoking history and 1 year
	TWA of oxygen saturation in blood values	Laboratory measurements	120 days
	TWA of body mass index values	Body measurements
Hepatitis 1y	Min, max, last value, TWA of aspartate aminotransferase (AST) values	Laboratory measurements	60 days
	Min, max, last value, TWA of ALT values
	Min, max, last value, TWA of alkaline phosphatase (ALP) values
	Min, max, last value, TWA of total bilirubin values
Colitis 1y	Rel freq of K50, K51, K52, K57, K58 codes	ICD-10 condition codes	1 year
	OH of chemotherapy administration indicator	Procedures
	OH of C43 code indicator	ICD-10 condition codes
	OH of anti–CTLA-4 drug indicator	Drugs
	OH of anti–PD-1 drug indicator	Drugs
	Freq of ICI drugs	Drugs
	Rel freqs of hemoglobin values below and above normal range	Laboratory measurements	120 days
	Rel freqs of albumin values below and above normal range
	Rel freqs of red blood cell values below and above normal range
	Rel freqs of absolute lymphocytes count values below and above normal range
	Rel freqs of white blood cell values below and above normal range
OS 1y	Freq of chemotherapy instances	Procedures	1 year
	Last value, TWA of albumin values	Laboratory measurements	120 days
	Last value of neutrophils % values
	Last value of lymphocytes % values
	Last value of lactate dehydrogenase (LDH)
	Last value, time-weighted average of alkaline phosphatase values
	Average difference of alanine transaminase values
	Average difference of packed cell volume % values
	Last value of oxygen saturation in blood
	Frequency of C78 codes	ICD-10 condition codes	1 year
	Age in years	Demographics	At first ICI

Abbreviations: freq, frequency; ICD, International Classification of Diseases; ICI, immune checkpoint inhibitor; OH, one-hot encoding; OS, overall survival; rel freq, relative frequency; TWA, time-weighted average.

^aCodes collapsed to a single indicator due to clinical reasoning (all codes lung-related). Details on feature types and descriptions of the ICD-10 codes can be found in the Data Supplement. Feature contributions are shown in Data Supplement (Fig S1).