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

Qun Mai; C D'Arcy J Holman; Frank M Sanfilippo; Jonathan D Emery; David B Preen

doi:10.1186/1741-7015-9-118

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

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.

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