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Table 1 Summary of study methods

From: Mental illness related disparities in diabetes prevalence, quality of care and outcomes: a population-based longitudinal study

A. Data sources for the study
Data sources Period Records Persons Key variables
1. Medicare benefits (MBS) 1984 to 2006 143,416,764 554,541 GP and pathology services
2. Pharmaceutical benefits (PBS) 1990 to 2006 78,467,656 475,826 Prescriptions
3. Hospital inpatients* 1980 to 2006 4,844,745 520,236 Dates, diagnoses and procedures
4. Mental health registry (MHR)     Dates and diagnoses
   - Mental health inpatients* 1966 to 2006 529,935 150,401  
   - Mental health outpatients and community 1971 to 2006 9,981,236 190,440  
5. Electoral roll registrations 1988 to 2006 782,161 483,524 Date of registration and updates
6. Death* 1990 to 2006 80,546 80,546 Date of death and cause of death
7. Emergency department* 2001 to 2006 990,506 248,457 Date of attendance and diagnosis
B. Data sources and codes for identifying diabetes
Hospital inpatient and ED ICD-9 code in any diagnosis field
   - Diabetes 250
   - Polycystic ovary syndrome 256.4
PBS Item
   - Oral hypoglycaemic agents 1202, 1801, 2178, 2430, 2440, 2449, 2607, 2720, 2939, 2940, 8188, 8189, 8391, 8392, 8450, 8451, 8452, 8533, 8535, 8607, 8687, 8688, 8689, 8690, 8691, 8692, 8693, 8694, 8695, 8696, 8810, 8811, 8838, 8884
   - Insulin 1425, 1426, 1429, 1430, 1431, 1461, 1462, 1531, 1532, 1533, 1534, 1535, 1537, 1591, 1592, 1710, 1711, 1713, 1715, 1716, 1718, 1721, 1722, 1761, 1762, 1763, 2061, 2062, 8006, 8084, 8085, 8212, 8390, 8435, 8571, 8609, 8874, 9039, 9094
MBS Item
   - GP diabetes annual cycle of care 2517, 2518, 2521, 2522, 2525, 2526, 2620, 2622, 2624, 2631, 2633, 2635
   - HbA1c or fructosamine 66551, 66554, 66557, 66319, 66322, 73815, 73840
C. Category of mental disorders
Category ICD-9 principal code
   - Alcohol/drug disorders 291, 292, 303 to 305
   - Schizophrenia 295
   - Affective psychoses 296
   - Other psychoses 293, 294, 297 to 299
   - Neurotic disorders 300
   - Personality disorders 301
   - Adjustment reaction 309
   - Depressive disorder 311
   - Other mental disorders 302, 306 to 308, 310, 312 to 319
   - Other than mental or behavioural disorders not in 290 to 319
D. MBS items for identifying pathology tests for routine diabetes monitoring
Test Item
Glycated haemoglobin (HbA1c) 66551, 66319
Microalbuminuria 66361, 66560
Lipids 66317, 66334, 66335, 66337, 66339, 66341, 66521, 66524, 66527, 66530, 66533, 66536
E. ICD-9 codes for identifying diabetes complications and diabetes-related deaths
  ICD-9 principal diagnosis or procedure codes
Diabetes/diabetes complications 250
Circulatory disorders     
   - Hypertension 401 to 405
   - Ischemic heart disease 410 to 414
   - Cerebrovascular disease 430 to 438, 362.34, 784.3
   - Heart failure 428, 429.2 to 429.3, 429.9
   - Atherosclerosis 440
   - Peripheral vascular disease 443, 459.8 to 459.9, 444, 447.1
Visual disorders     
   - Glaucoma 365
   - Cataract 366
   - Blindness 369
Other disorders     
   - Nephropathy 580 to 586, V45.1, V56
Other renal complications     
   - Infections of kidney 590
   - Cystitis, urinary tract infection 595, 599.0
   - Proteinuria 791.0
   - Neuropathy/other neurologic symptoms 354, 355, 356.8, 729.2
   - Chronic skin ulcer 707
   - Gangrene 785.4
   - Nontraumatic lower-extremity amputation 84.1, 84.3
Other complications     
   - Candidiasis of vulva and vagina 112.1
   - Chronic osteomyelitis of the foot 730.17
  1. Abbreviations: ED, emergency department; ICD-9, The International Classification of Diseases, ninth revision* In these datasets, ICD-9 was used for 1980-1987, ICD-9-CM for 1988 to June 1999, and ICD-10-AM from July 1999 onwards. We back mapped ICD-9-CM and ICD-10-AM codes to corresponding ICD-9 codes for this study.