
Building a microsimulation model of heroin use careers in Australia
Tables
Mutually exclusive states and their definition.
State | Definition |
---|---|
Abstinence (S1) | Individuals in this state are not using heroin but have used heroin at some previous time. |
Irregular use (S2) | Individuals in this state use heroin irregularly, as defined as 1 to 3 days a month, or a maximum of 1 or 2 days a week. They do not ever develop dependence. |
Regular/dependent heroin use (S3) | Individuals in this state use heroin regularly (defined as more than 3 days per week in the last month) and they are not in receipt of any type of treatment. |
Withdrawal (S4) | Individuals in this state receive withdrawal treatment for their heroin dependence. Withdrawal treatment is concerned with neuro-adaptation reversal, involves about 5–7 days care (in an inpatient or outpatient setting) and includes medications to manage symptoms, supportive care and case management. In this model it is characterised as residential withdrawal (for the purposes of unit costing), and excludes long-tern tapered methadone withdrawal. |
Residential rehabilitation (RR) (S5) | Individuals in this state receive residential rehabilitation for their heroin dependence. RR is concerned with behavioural change across all life areas, including relapse prevention, psychological wellbeing, physical health, nutrition etc. It is provided in residential settings, and an ideal treatment program is 6–9 months long although many will leave in the first week. While some RR in Australia also provide OST as part of the program, as characterised here this RR does not include OST. |
Opioid Substitution Treatment (OST) (S6) | Individuals in this state receive Opioid Substitution Treatment for their heroin dependence. The provision of a legal, safe opioid (either methadone or buprenorphine), dispensed daily or less frequently with take-away doses; requires a prescriber and attendance at a pharmacy (primary care or clinic settings). The model does not distinguish between methadone and buprenorphine. |
Counselling Only (S7) | Individuals in this state receive counselling for their heroin dependence. Provision of psychological therapy only, on an outpatient basis (weekly or fortnightly) with case management. |
In-prison no treatment (S8) | Individuals in this state are in prison; and have a history of heroin use. |
In-prison treatment (OST) (S9) | Individuals in this state are in prison, have a history of heroin use, and are in receipt of OST in prison. |
Initial population by state.
State | Starting number |
---|---|
S1 abstinent | 22,000 |
S2 irregular ongoing use | 53,000 |
S3 regular, dependent use | 16,500 |
S4 withdrawal | 20 |
S5 Therapeutic community | 80 |
S6 OST | 17,500 |
S7 counselling | 100 |
S8 prison not in treatment | 1,100 |
S9 prison in treatment | 1,100 |
TOTAL starting population | 111,400 |
ATOS transition probabilities.
Current state | ||||||||
---|---|---|---|---|---|---|---|---|
State 1 | State 2+3 | State 4 | State 5 | State 6 | State 7 | Sum | ||
Previous state | State 4 | 0.1822 | 0.4186 | 0.0000 | 0.1124 | 0.2209 | 0.0659 | 1 |
State 5 | 0.4383 | 0.2222 | 0.0370 | 0.0000 | 0.1358 | 0.1667 | 1 | |
State 6 | 0.4015 | 0.4891 | 0.0219 | 0.0146 | 0.0000 | 0.0730 | 1 | |
State 7 | 0.4203 | 0.3188 | 0.0580 | 0.0435 | 0.1594 | 0.0000 | 1 |
Final base transition probabilities used in the model.
From: | To: | S1 | S2 | S3 | S4 | S5 | S6 | S7 |
---|---|---|---|---|---|---|---|---|
S1 Abstinence | 1.0 | |||||||
S2 Irregular use | 1.0 | |||||||
S3 Dependence | 0.04 | 0.01 | 0.03 | 0.90 | 0.02 | |||
S4 Withdrawal | 0.18 | 0.52 | 0.05 | 0.20 | 0.05 | |||
S5 Residential rehab | 0.40 | 0.40 | 0.10 | 0.10 | ||||
S6 OTP | 0.40 | 0.55 | 0.02 | 0.01 | 0.02 | |||
S7 Counselling | 0.30 | 0.50 | 0.05 | 0.05 | 0.10 |
Summary of data sources for LOS estimation.
State | LOS data sources |
---|---|
S1: Abstinence | ATOS Dataset, (Hser, 2007; Nosyk et al., 2013; Shah, Galai, Celentano, Vlahov, & Strathdee., 2006; Simpson & Marsh, 1986; Termorshuizen, Krol, Prins, & Van Ameijden, 2005) |
S2: Irregular use | ATOS Dataset, (Coffin & Sullivan, 2013; Grönbladh & Gunne, 1989) |
S3: Regular use | ATOS Dataset, (Bell et al., 2006) |
S4: Withdrawal | ATOS Dataset Alcohol and Other Drug Treatment Services National Minimum Data Set (AODTS-NMDS) Dataset |
S5: Residential Rehab | ATOS Dataset AODTS-NMDS Dataset |
S6: OTP | ATOS Dataset, (Burns et al., 2009) |
S7: Counselling | ATOS Dataset AODTS-NMDS Dataset |
S8, S9: Prison states | All LOS determined by crime type (probability) and then the average sentence for that crime type (BOCSAR Court Data Report, 2012, see NSW Bureau of Crime Statistics and Research. http://www.bocsar.nsw.gov.au). |
Crude mortality rates for individuals based on the state and length of stay.
State: To | State: From | LoS | CMR (Crude Mortality Rate) (all cause) | Source |
---|---|---|---|---|
S1 | Any | Fixed rate across LoS | 5.3 /1000 PY (5.0–5.6) | (Degenhardt et al., 2009) |
S2 | Any | Fixed rate across LOS | 5.3/1000 PY (5.0–5.6) | (Degenhardt et al., 2014; Degenhardt et al., 2009) |
S3 | S1, S4, S5, S7 | 1st week 2nd week |
17.4/1000 PY (11.7–25.0) 20.1/1000 PY (13.8–28.4) |
(Degenhardt et al., 2009) |
S8 | 1st 2 weeks out of prison | 59.5/1000 PY (41.3–83.6) | (Degenhardt et al., 2014) | |
S2, S6, S9 | For the rest of LoS | 11.5/1000 PY (11.1–12.0) | (Degenhardt et al., 2009) | |
S4 | Anywhere | Fixed | 6.0/1000 PY (5.7–6.4) | |
S5 | Anywhere | Fixed | 6.0/1000 PY (5.7–6.4) | |
S6 | S3, S4, S5, S7, S8 | 1st week of LoS 2nd week |
39.5/1000 PY (31.9–48.8) 17.0/1000 PY (11.8–23.6) |
|
S9 | 1st week of LoS | 10.9/1000 PY (4.0–23.8) | (Degenhardt et al., 2014) | |
S6 | All other times | 5.6/1000 PY (5.2–5.9) | (Degenhardt et al., 2009) | |
S7 | S3, S4, S5, S6 | Fixed | 6.0/1000 PY (5.7–6.4) | |
S8 | Any | Fixed | 2.7/1000 PY (1.2–2.2) | (Larney et al., 2014) |
S9 | Any | Fixed | 0.7/1000 PY (0.3 to 1.2) |
Heroin treatment costs.
State | tSate description | Per day costs (AUD) |
---|---|---|
S1 | Abstinence | $0.00 |
S2 | Irregular Use | $0.00 |
S3 | Dependent Use No Treatment | $0.00 |
S4 | Withdrawal | $410.77 |
S5 | Residential Rehab | $139.36 |
S6 | Opioid Treatment Program | $27.09 |
S7 | Counselling | $18.49 |
S9 | Prison treatment | $224.81 |
Other healthcare costs.
State | State name | Per month costs (AUD) |
---|---|---|
S1 | Abstinence | $649.00 |
S2 | Irregular Use | $649.00 |
S3 | Dependent Use No Treatment | $441.00 |
S4 | Withdrawal | $648.00 |
S5 | Residential Rehab | $392.00 |
S6 | Opioid Treatment Program | $860.00 |
S7 | Counselling | $566.00 |
S8 | Prison No Treatment | $0.00 |
S9 | Prison Treatment | $0.00 |
HIV and HCV treatment costs in AUD (per person per year).
HIV treatment costs | $20,678 |
HCV treatment costs | $15,526 |
Crime costs (AUD) per offence.
Crime type | Police costs | Social costs |
---|---|---|
Homicide and related offences | $ 13,484.80 | $2,731,649.19 |
Acts intended to cause injury | $3,038.83 | $2,650.68 |
Sexual assault and related offences | $ 4,178.39 | $3,959.32 |
Dangerous or negligent acts endangering persons | $2,469.05 | $2,904.72 |
Abduction and other offences against the person | $4,273.35 | $2,904.72 |
Robbery or extortion and related offences | $7,312.18 | $5,179.91 |
Unlawful entry or burglary or break and enter | $3,988.46 | $1,060.68 |
Theft and related offences | $3,228.76 | $2,883.83 |
Fraud or deception and related offences | $3,133.79 | $506.05 |
Illicit drug offences | $2,753.94 | 0 |
Prohibited and regulated weapons offences | $3,228.76 | 0 |
Property damage and environmental pollution | $2,564.01 | $1,060.68 |
Public order offences | $3,703.57 | $97.16 |
Traffic and vehicle regulatory offences | $1,139.56 | $97.16 |
Offences against justice procedures | $3,703.57 | $97.16 |
Miscellaneous offences | $2,012.00 | 0 |
COURT COST (Fixed) | $7,712 |
Capturing the resources relating to those who are charged and found not guilty and those who are found guilty but do not go to prison.
2012 AUD – weighted by distribution of offences | Applied to | |
---|---|---|
Police costs | $3,090 | • those found not guilty • those found guilty and not sentenced to prison |
Court costs | $7,712 | • those found not guilty • those found guilty and not sentenced to prison |
Social costs | $1,144 | • those found guilty and not sentenced to prison |
Comparison of computed mortality rates from simulation and input rates.
State | Mortality rate from simulation | Input mortality rate (CI interval 95%) |
---|---|---|
S1 | 0.0057 | 0.005 – 0.0056 |
S2 | 0.0060 | 0.005 – 0.0056 |
S3 | 0.0106 | 0.0111 – 0.0120 |
S4 | 0.0047 | 0.0057 – 0.0064 |
S5 | 0.0061 | 0.0057 – 0.0064 |
S6 | 0.0057 | 0.0052 – 0.0059 |
S7 | 0.0056 | 0.0057 – 0.0064 |
S8 | 0.0024 | 0.002 – 0.0037 |
S9 | 0.00038 | 0.0003 – 0.0012 |
Comparison of computed imprisonment rates from simulation and input rates.
From Simulation | From the Input data | |||
---|---|---|---|---|
To S8 | To S9 | To S8 | To S9 | |
S1 | 0.0022 | - | 0.0026 | - |
S2 | 0.0286 | - | 0.0282 | - |
S3 | 0.0404 | 0.0456 | 0.0408 | 0.0408 |
S4 | 0.0414 | 0.0429 | 0.0408 | 0.0408 |
S5 | 0.0400 | 0.0430 | 0.0408 | 0.0408 |
S6 | - | 0.0784 | - | 0.0816 |
S7 | 0.0427 | 0.0395 | 0.0408 | 0.0408 |
Comparison of computed imprisonment rates from simulation and input rates.
Simulation output | Input rates | ||||||||||||||
---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
S1 | S2 | S3 | S4 | S5 | S6 | S7 | S1 | S2 | S3 | S4 | S5 | S6 | S7 | ||
S1 | - | - | 1 | - | - | - | - | S1 | - | - | 1 | - | - | - | - |
S2 | 1 | - | - | - | - | - | - | S2 | 1 | - | - | - | - | - | - |
S3 | 0.16 | - | - | 0.02 | 0.03 | 0.76 | 0.03 | S3 | 0.154 | - | - | 0.015 | 0.048 | 0.750 | 0.033 |
S4 | 0.18 | - | 0.52 | - | 0.05 | 0.20 | 0.05 | S4 | 0.18 | - | 0.52 | - | 0.05 | 0.20 | 0.05 |
S5 | 0.60 | - | 0.33 | - | - | 0.03 | 0.04 | S5 | 0.60 | - | 0.34 | - | - | 0.04 | 0.04 |
S6 | 0.39 | - | 0.56 | 0.02 | 0.01 | - | 0.02 | S6 | 0.40 | - | 0.55 | 0.02 | 0.01 | - | 0.02 |
S7 | 0.30 | - | 0.50 | 0.05 | 0.05 | 0.10 | - | S7 | 0.30 | - | 0.50 | 0.05 | 0.05 | 0.10 | - |
S8 | 0.30 | - | 0.60 | - | - | 0.10 | - | S8 | 0.30 | - | 0.60 | - | - | 0.10 | - |
S9 | - | - | 0.10 | - | - | 0.90 | - | S9 | - | - | 0.10 | - | - | 0.90 |