icd9_chapters, icd9_chapters_sub and icd9_majors contain
mappings from the higher level descriptions of ICD-9 codes to the ranges of
ICD-9 codes they describe. Helpful in summarizing codes or grouping for
human-readable output. These can easily be converted to a co-morbidity
mapping, as shown in the vignette.
http://www.cms.gov/Medicare/Coding/ICD9ProviderDiagnosticCodes/codes.html
001-139 Infectious And Parasitic Diseases
140-239 Neoplasms
240-279 Endocrine, Nutritional And Metabolic Diseases, And Immunity Disorders
280-289 Diseases Of The Blood And Blood-Forming Organs
290-319 Mental Disorders
320-389 Diseases Of The Nervous System And Sense Organs
390-459 Diseases Of The Circulatory System
460-519 Diseases Of The Respiratory System
520-579 Diseases Of The Digestive System
580-629 Diseases Of The Genitourinary System
630-679 Complications Of Pregnancy, Childbirth, And The Puerperium
680-709 Diseases Of The Skin And Subcutaneous Tissue
710-739 Diseases Of The Musculoskeletal System And Connective Tissue
740-759 Congenital Anomalies
760-779 Certain Conditions Originating In The Perinatal Period
780-799 Symptoms, Signs, And Ill-Defined Conditions
800-999 Injury And Poisoning
V01-V91 Supplementary Classification Of Factors Influencing Health Status And Contact With Health Services
E000-E999 Supplementary Classification Of External Causes Of Injury And Poisoning
Format: list with chapter/sub-chapter or major names stored in list names, each with two element named character vector with start and end codes.