Table 1

ICD-9 classification and diagnosis groups used in the present study
Main category ICD-9-CM classification The 30 diagnosis groups
Infectious and Parasitic Diseases 1 Acute infectious and parasitic diseases and poisoning
2 Chronic infectious and parasitic diseases (tuberculosis, HIV, hepatitis)
Neoplasms 3 Neoplasms
Endocrine, Nutritional, and Metabolic Diseases and Immunity Disorders 4 Diabetes
5 Endocrine, metabolic and immunity disorders
Diseases of Blood and Bloodforming Organs 6 Haematology
Mental Disorders 7 Acute mental disorders (i.e. psychosis)
8 Chronic mental disorders (i.e. rehabilitation programs, personality disorders)
Diseases of the Nervous System and Sense Organs 9 Diseases of the nervous system
10 Eyecare
11 Earcare
Diseases of the Circulatory System 12 Cerebral hemorrhage and ischemia
13 Chronic cardiovascular disease (including congestive heart failure)
14 Cardiovascular disease with intervention (PCI/CABG)
Diseases of the Respiratory System 15 Acute diseases of the respiratory system (i.e. pneumonia and influenza)
16 Complex pulmonary surgery
17 Common surgery of the respiratory system (i.e. tonsillitis)
18 Chronic obstructive pulmonary disease and allied conditions
Diseases of the Digestive System 19 Surgery of diseases of the digestive system
20 Diseases of oral cavity, salivary glands, and jaws
Diseases of the Genitourinary System 21 Gynaecology
22 Urinary system
Complications of Pregnancy, Childbirth, and the Puerperium 23 Complications of pregnancy, childbirth, and the puerperium
Diseases of the Skin and Subcutaneous Tissue 24 Dermatology
Diseases of the Musculoskeletal and Connective Tissue 25 Rheumatism and arthropathies (non surgical)
26 Diseases of the musculoskeletal system that require surgical treatment
Congenital Anomalies 27 Congenital disorders
Newborn (Perinatal) 28 Certain conditions originating in the perinatal period
Injury and Poisoning 29 Emergency care (distorsion, luxation, common fractures)
30 Specialized trauma care (injuries of organs, complex fractures)

Ikkersheim et al.

Ikkersheim et al. BMC Health Services Research 2013 13:220   doi:10.1186/1472-6963-13-220

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