Figures and tables in Challenges and solutions in constructing a microsimulation model of the use and costs of medical services in Australia

Abstract

This paper describes the development of a microsimulation model ‘HealthMod’ which simulates the use and costs of medical and related services by Australian families. Australia has a universal social insurance scheme known as ‘Medicare’ which provides all Australians with access to free or low-cost essential medical services. These services are provided primarily by general practitioners as well as specialist doctors but also include diagnostic and imaging services. Individuals may pay a direct out-of pocket contribution if fees charged for services are higher than the reimbursement schedule set by government. HealthMod is based on the Australian 2001 National Health Survey. This survey had a number of deficiencies in terms of modelling the national medical benefits scheme. The article outlines three major methodological steps that had to be taken in the model construction: the imputation of synthetic families, the imputation of short-term health conditions, and the annualisation of doctor visits and costs. Some preliminary results on the use of doctor services subsidised through Australia’s Medicare are presented.

This article contains 1 figure and 10 tables.

Figures

**Figure 1.** Distribution of number of short term health conditions per person.

Tables

Table 1. Medicare subsidised medical services and benefits paid by MBS category (processed by Medicare Australia July 2005 to June 2006).

MBS Category	No. Services (‘000,000)	Benefit ($m)	No. Services per 1,000 pop.	Benefit ($) per 1,000 pop.
1 Professional Attendances	1,260.5	5,266.0	6,118.3	255,602.7
2 Diagnostic Procedures and Investigations	43.3	251.2	210.3	12,190.9
3 Therapeutic Procedures	153.4	1,790.6	744.7	86,914.5
4 Oral and Maxillofacial Services (by Approved Dental Practitioners)	0.7	8.5	3.6	414.4
5 Diagnostic Imaging Services	149.2	1,609.4	724.3	78,118.7
6 Pathology Services	828.9	1,641.8	4,023.3	79,693.0
7 Cleft Lip and Cleft Palate	0.1	1.3	0.3	61.9
8 Miscellaneous Services	37.5	407.4	181.9	19,776.4
Total	2,473.7	10,976.3	12,006.9	532,772.5

Source: Medicare Australia website @ www.medicareaustralia.gov.au

Table 2. Closeness of match – age group (percentage distribution).

Age Group (years) – STINMOD /01A	Age Group (years) – NHS
Age Group (years) – STINMOD /01A	0–4	5–9	10–14	15–19	20–24	25–29	30–34	35–39	40–44	45–49	50–54	55–59	60–64	65–69	70–74	75+
0–4	79.0	18.6	2.4	.	.	.	.	.	.	.	.	.	.	.	.	.
5–9	14.4	65.4	20.1	.	.	.	.	.	.	.	.	.	.	.	.	.
10–14	4.6	17.7	77.7	.	.	.	.	.	.	.	.	.	.	.	.	.
15–19	.	.	.	69.7	13.4	7.7	5.2	0.8	0.8	0.4	1.1	0.8	0.1	0.1	.	.
20–24	.	.	.	26.2	28.1	18.0	8.1	5.2	6.7	3.3	1.0	1.9	1.0	0.3	0.1	.
25–29	.	.	.	7.1	15.2	32.8	22.0	5.7	3.8	5.1	3.3	1.5	2.6	0.8	0.2	.
30–34	.	.	.	2.1	6.6	9.1	40.6	21.2	6.2	6.4	3.8	1.2	0.8	0.8	0.6	0.6
35–39	.	.	.	1.2	2.7	5.8	6.7	45.0	19.4	7.6	5.0	2.6	1.3	0.9	0.6	1.0
40–44	.	.	.	0.9	1.9	3.5	5.3	10.6	43.6	15.3	10.1	3.1	2.1	1.5	1.4	0.5
45–49	.	.	.	0.9	1.2	1.6	1.7	4.6	14.2	38.2	20.4	7.4	2.6	3.1	2.4	1.7
50–54	.	.	.	0.1	1.0	0.8	1.0	2.8	5.8	11.9	32.4	30.4	7.5	2.4	1.1	2.9
55–59	.	.	.	.	0.4	0.3	1	1.0	2	4.7	8.6	31.8	36.1	6.4	2.8	4.8
60–64	.	.	.	.	0	.	0.0	0.2	0.5	1.5	2.3	5.4	39.0	41.8	5.0	4.2
65–69	.	.	.	.	.	.	0.1	0.2	0.3	0.5	1.0	2.3	6.2	31.7	50.3	7.4
70–74	.	.	.	.	0.1	0.1	.	0.1	0.2	1	1.7	3.6	3.2	3.3	37.5	49.3
75+	.	.	.	.	.	.	.	0.0	0.3	0.0	0.9	1.4	3.2	1.5	3.2	89.2
All	9.1	8.5	6.6	6.5	4.7	5.8	7.1	8.0	7.9	6.8	6.1	5.3	4.8	3.9	3.8	5.3

Table 3. Closeness of match – equivalent income deciles (percentage distribution).

Equivalent income decile – STINMOD/01A	Equivalent Income decile – NHS
Equivalent income decile – STINMOD/01A	1	2	3	4	5	6	7	8	9	10
1	69.9	16.4	13.3	0	0.1	0.1	0.2	.	.	.
2	20.5	46.3	33	.	.	0.1	0.1	.	.	.
3	7.1	24.9	67.5	.	.	0.3	0.3	.	.	.
4	.	.	.	39.4	22.6	28.4	9.6	.	.	.
5	.	.	.	19.1	29.1	23.7	28.0	.	.	.
6	.	.	.	12.3	20.3	37.4	30.0	.	.	.
7	.	.	.	2.4	9.7	18.0	69.9	.	.	.
8	.	.	.	.	.	.	.	67.7	30.3	1.9
9	.	.	.	.	.	.	.	18.6	47.3	34.1
10	.	.	.	.	.	.	.	12.3	23.6	64.1

Table 4. Closeness of match – number of persons in household (percentage distribution).

Number of persons in household – STINMOD/01A	Number of persons in household – NHS
Number of persons in household – STINMOD/01A	1	2	3	4	5	6+
1	67.0	14.9	8.0	4.4	3.0	2.6
2	10.0	75.8	9.7	3.3	0.9	0.3
3	3.4	16.5	54.1	23.2	2.5	0.3
4	1.8	1.4	17.1	61.2	14.9	3.7
5	1.5	0.9	2.6	35.1	44.6	15.4
6+	9.1 12.8	1.3 26.6	2.4 18.2	7.5 25	29.4 11.7	50.2
All	12.8	26.6	18.2	25	11.7	5.7

Table 5. Closeness of match – income unit type (percentage distribution).

Income Unit Type -STINMOD/01A	Income Unit Type – NHS
Income Unit Type -STINMOD/01A	Lone person	Couple	Couple with kids	Single with kids	Other
Lone person	69.7	.	.	.	30.3
Couple	.	100	.	.	.
Couple with kids	.	.	100	.	.
Single with kids	.	.	.	100	.
Other	55.2	.	.	.	44.8
All	18	7.1	23.1	42.4	9.4

Table 6. Prevalence and long-term characteristics of health condition groups, 1995.

Health Name	Condition	Prevalence per 100 population	Prevalence as a LTC per 100 population	% LTC (either only or with acute bouts)
1	arthritis	14.72	14.58	99.05
2	asthma	11.30	11.09	98.10
3	diabetes	2.47	2.45	99.15
4	heart and circulatory	21.42	20.02	93.45
5	mental health	5.80	4.00	69.04
6	cancer	2.10	1.78	84.58
7	injury and poisoning	6.39	0.60	9.43
8	other muscular	17.01	12.48	73.36
9	other endocrine	10.47	7.81	74.66
10	respiratory	32.26	23.12	71.66
11	visual disturbances	0.27	0.19	72.43
12	other eye and adnexa	49.71	48.87	98.31
13	ear and mastoid	12.48	11.36	91.09
14	nervous system	3.50	2.65	75.81
15	infectious disease	3.73	1.03	27.66
16	digestive	10.56	7.66	72.60
17	dental	5.06	0.12	2.44
18	genito-urinary	6.38	3.60	56.34
19	skin and subcutaneous	9.87	3.80	38.45
20	blood diseases	2.05	1.67	81.67
21	pregancy and childbirth	0.88	0.15	17.05
22	sign and symptoms	24.24	7.30	30.12
23	preventative	31.92	0.02	0.06
24	congential	0.37	0.34	90.04
25	disability nec	1.16	1.12	96.55
26	unspecified symptoms	4.03	2.56	63.52

Note: LTC = Long Term Condition; NEC = not elsewhere classified.

Source: ABS 1995 NHS.

Table 7. Likelihood of having a short-term health condition.

Variable	Crude Odds Ratio	Comment on crude odds ratio	Odds Ratio (adjusted for age and sex)	Odds ratio (adjusted for age, sex and SAHS)
Age group (treated as a continuous variable)	1.129	Significant, appears to have close to linear relationship
Sex 1 Male vs 2 Female	0.60	Significant
Equivalent Income decile		Significant as a group but non linear
0 NA	0.759		0.753	0.707
1 1st decile	0.630		0.742	0.661
2	0.881		0.844	0.693
3	1.078		0.948	0.767
4	0.988		0.963	0.837
5	0.769		0.863	0.777
6	0.675		0.747	0.682
7	0.713		0.810	0.752
8	0.812		0.894	0.846
9	0.810		0.858	0.827
10 10th decile	1		1	1
Self Assessed Health Status		Significant as a group
0 NA	0.040		0.113
1Excellent	0.056		0.081
2	0.082		0.116
3	0.111		0.146
4	0.264		0.307
5 Poor	1		1
Marital Status		Significant as a group
1 Married	2.122		0.911	0.977
2 de facto	1.759		1.081	1.100
3 separated	2.186		0.992	0.986
4 divorced	2.697		1.040	1.084
5 widowed	6.316		1.258	1.259
6 never married	1		1	1
Income unit type
1 Married with dep kids	0.467		0.509	0.522
2 Married without dep kids	1.208		0.677	0.672
3 Single parent with dep kids	0.447		0.509	0.507
4 Single	0.749		0.569	0.555
5 Out of scope	0.707		0.641	0.623
9 Incomplete unit	1		1	1
Education		Significant
0 Not have higher	1		1	1
qualification	1.46		0.877	0.80
1 Has higher qualification
Labour force status		Significant as a group
0 NA	0.639		0.977	1.528
1 Unemployed	0.769		0.819	0.955
2 Employed	0.580		0.712	0.698
3 Not in labour force	1		1	1
Concession card holder (under 1995 rules)		Significant as a group
0 NA	0.630		1.245	0.080
1 Covered	2.525		1.744	1.494
2 Not covered	1.241		1.176	1.203
3 Don’t Know	1		1	1
Government benefit recipient 1 Yes vs 2 No	2.522	Significant	1.406	1.110

Source: ABS 1995 NHS.

Table 8. Distribution of frequency of a doctor’s visit, 2001.

Frequency of Doctor’s Visit	HealthMod	No.%	NHS95	No.%	Absolute Difference	% Diff.
1	3,533,937	77.35	3,231,795	76.83	302,142	9.35
2	828,385	18.13	732,739	17.42	95,646	13.05
3	142,938	3.13	144,020	3.42	1,082	0.75
4	49,542	1.08	60,825	1.45	11,283	18.55
5	9,593	0.21	17,051	0.41	7,458	43.74
6	748	0.02	7,735	0.18	6,987	90.33
7	2,201	0.05	5,620	0.13	3,419	60.83
8	0	0.00	281	0.01	281	100.00
9 and over	1,213	0.03	6,507	0.15	5,294	81.36

Table 9. Primary reasons for a doctor’s visit, 2001.

Condition Group Name		HealthMod		NHS95		Absolute Difference	% Diff.
Condition Group Name		No.	%	No.	%	Absolute Difference	% Diff.
1	Arthritis	83,102	1.8	80,294	1.92	2,808	3
2	Asthma	92,614	2.0	85,203	2.04	7,411	9
3	Diabetes	50,058	1.1	36,357	0.87	13,701	38
4	Heart & Circulatory Dis.	222,438	4.9	248,960	5.95	26,522	11
5	Mental Health	237,551	5.2	101,921	2.44	135,630	133
6	Cancer	47,680	1.0	67,662	1.62	19,982	30
7	Injury and Poisoning	404,858	8.9	230,795	5.52	174,063	75
8	Other Musculoskeletal	484,887	10.6	258,942	6.19	225,945	87
9	Other endocrine	82,916	1.8	68,879	1.65	14,037	20
10	Respiratory	661,795	14.5	713,950	17.07	52,155	7
12	Eye and adnexa	70,612	1.5	71,758	1.72	1,146	2
13	Ear and mastoid	114,307	2.5	128,297	3.07	13,990	11
14	Nervous system	99,963	2.2	47,965	1.15	51,998	108
15	Infectious disease	145,684	3.2	103,486	2.47	42,198	41
16	Digestive	125,438	2.7	151,064	3.61	25,626	17
18	Genitor-urinary	85,042	1.9	131,022	3.13	45,980	35
19	Skin and subcutaneous	200,967	4.4	233,831	5.59	32,864	14
20	Blood disease	11,717	0.3	14,214	0.34	2,497	18
21	Pregnancy and childbirth	40,170	0.9	76,677	1.83	36,507	48
22	Signs and symptoms	273,554	6.0	252,137	6.03	21,417	8
23	Preventative	1,024,505	22.4	1,041,530	24.9	17,025	2
24	Congenital abnormality	7,624	0.2	4,127	0.1	3,497	85
25	Disability	204	0.0	2,383	0.06	2,179	91
26	Other	872	0.0	31,047	0.74	30,175	97

Table 10. Total doctor services, by broad type of service, 2001.

BTOS	Name	Medicare Aust.	HealthMod	Absolute Difference	% Difference
0101	Un-referred attendances – GP	91,952,523	95,998,090	4,045,567	4.4
0102	Un-referred attendances -enhanced primary care	323,056	503,860	180,804	56.0
0103	Un-referred attendances – other	8,059,031	9,321,414	1,262,383	15.7
0200	Specialist attendances	19,656,169	19,164,702	491,467	−2.5
0300	Obstetrics	1,470,160	1,459,591	10,569	−0.7
0400	Anaesthetics	2,140,921	1,979,525	161,396	−7.5
0700	Operations	6,039,494	6,726,906	687,412	11.4
0800	Assistance at operations	279,281	309,925	30,644	11.0
1000	Radiotherapy and therapeutic nuclear medicine	642,033	599,165	42,868	−6.7
1100	Miscellaneous	5,525,245	5,436,272	88,973	−1.6
Total		134,617,753	141,499,450	6,881,697	5.1