Background
Methods
Data sources
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 |
Study cohorts
Variables and measurements
Exposure variables
Outcome measures
Recommended pathology tests
Other outcome measures
Potential confounders
Statistical analyses
Ethics approval
Results
Patient characteristics
Patient characteristic* | MHCs (n = 17,045) | Non MHCs (n = 26,626) |
---|---|---|
Age, years, % | ||
< 45 | 20.7% | 11.5% |
45 to 54 | 19.7% | 14.3% |
55 to 64 | 21.6% | 20.7% |
65 to 74 | 18.6% | 23.2% |
≥75 | 19.3% | 30.3% |
Sex, % male | 41.9% | 43.8% |
Indigenous status, % | ||
Indigenous | 11.8% | 5.6% |
Non-Indigenous | 88.1% | 91.1% |
Missing | 0.1% | 3.3% |
Level of social disadvantage | ||
Most disadvantaged | 15.1% | 10.5% |
More disadvantaged | 22.7% | 21.1% |
Little disadvantaged | 24.5% | 23.8% |
Less disadvantaged | 17.3% | 17.8% |
Least disadvantaged | 19.0% | 25.8% |
Missing | 1.3% | 1.0% |
Residential remoteness | ||
Metropolitan | 64.8% | 70.9% |
Rural | 25.0% | 22.7% |
Remote | 9.8% | 6.3% |
Missing | 0.4% | 0.1% |
Charlson comorbidity score, mean (SD) | 0.83 (1.62) | 0.63 (1.43) |
Diabetes recorded before T0, % | 34.8% | 31.6% |
Type of treatment at one year, % | ||
No diabetic medications | 53.1% | 52.5% |
Oral hypoglycemic agents only | 39.0% | 40.9% |
Insulin | 7.9% | 6.6% |
Type of treatment at up to 16 years, % | ||
No diabetic medications | 33.6% | 32.6% |
Oral hypoglycemic agents only | 47.7% | 51.0% |
Insulin | 18.7% | 16.4% |
Type of mental disorders | ||
- Alcohol/drug disorders | 8.7% | |
- Schizophrenia | 4.8% | |
- Affective psychoses | 18.6% | |
- Other psychoses | 10.7% | |
- Neurotic disorders | 17.6% | |
- Personality disorders | 2.2% | |
- Adjustment reaction | 5.1% | |
- Depressive disorder | 4.9% | |
- Other mental disorders | 5.9% | |
- Other than mental or behavioural disorders | 21.6% |
Diabetes prevalence
Measure | MHCs* | Non-MHCs | Unadjusted OR/RR (95% CI) | Adjusted OR/RR (95% CI)† |
---|---|---|---|---|
Diabetes prevalence‡, % | 9.3% | 6.1% | 1.41 (1.37 to 1.44) | 1.40 (1.36 to 1.43) |
Receipt of recommended test at one year§, % | ||||
- HbA1c test | 37.2% | 42.9% | 0.79 (0.76 to 0.82) | 0.84 (0.80 to 0.88) |
- Microalbuminuria test | 12.6% | 15.4% | 0.79 (0.74 to 0.84) | 0.76 (0.71 to 0.82) |
- Blood lipid test | 24.3% | 29.5% | 0.77 (0.73 to 0.80) | 0.81 (0.77 to 0.85) |
- Any test | 46.4% | 53.2% | 0.76 (0.73 to 0.80) | 0.81 (0.78 to 0.85) |
Receipt of recommended test during the entire follow-up period, rate per person per year | ||||
- HbA1c test | 0.62 | 0.68 | 0.89 (0.86 to 0.91) | 0.88 (0.86 to 0.90) |
- Microalbuminuria test | 0.24 | 0.27 | 0.86 (0.83 to 0.89) | 0.82 (0.80 to 0.85) |
- Blood lipid test | 0.40 | 0.44 | 0.90 (0.88 to 0.93) | 0.90 (0.88 to 0.93) |
- All tests | 1.25 | 1.38 | 0.88 (0.86 to 0.90) | 0.86 (0.84 to 0.88) |
First hospitalisation for diabetes complications, % | 45.2% | 45.0% | 1.08 (1.05 to 1.12) | 1.20 (1.17 to 1.24) |
Diabetes related mortality, % | 11.8% | 11.1% | 1.08 (1.02 to 1.15) | 1.43 (1.35 to 1.52) |
All cause mortality, % | 30.4% | 27.1% | 1.14 (1.10 to 1.19) | 1.47 (1.42 to 1.53) |
Entire follow-up time, y, mean (SD) | 10.5 (5.9) | 10.8 (5.6) |