NDARC Technical Report No. 285 (2007)

EXECUTIVE SUMMARY

Aims: This report examines total costs and costs trends over time for specific drug-related hospital separations in Australia from 1999/00 to 2004/05. The report presents data on the costs for people being treated in hospital for opioid-, amphetamine-, cannabis- and cocaine-related problems including the cost of separations which are considered to be “drug-caused” but not identified as so by the recorded ICD-10-AM codes.

Method: Hospital separation data from the National Hospital Morbidity Database (NHMD), coded according to the International Statistical Classification of Disease and Related Health Problems – 10th revision, Australian Modification (ICD-10-AM), were analysed for the period of 1999/00 to 2004/05. A patient’s hospital stay is coded according to the conditions which are considered to be significant in terms of treatment and resources used. All separations are also allocated an Australian Refined – Diagnostic Related Group (DRG). Each DRG has a cost weight allocated which is a reflection of resource use within that
DRG.

Separations with a drug-related (opioid, amphetamine, cannabis and cocaine) principal diagnosis and drug-related DRG were analysed. Appropriate DRG cost weights were applied. Both ‘current’ (at the time of separation) and ‘constant’ (adjusted for inflation to reflect prices of the reference year – 2004/05) are presented. Costs are reported separately for each drug class as well as the overall total and average cost per separation.

Costs were also calculated for hospital separations where the principal diagnosis was drugrelated but the DRG into which the separation was classified was not necessarily drugrelated (for instance, mechanical ventilation). Similarly, costs were also calculated for some separations which were considered to be “drug-caused” and estimated using established aetiological fractions. Average length of stay, cost by age group, and jurisdiction by drug type are provided.

Results
a) Overall costs
The main results for the overall costs include:

The total current costs by DRG for separations with a drug-related principal diagnosis ranged from $30.2 million in 1999/00 to $35.7 million in 2004/05.
Drug intoxication DRGs had the largest expenditure ($9.6 million in 2000/01 to $14.6 million in 2004/05).
The total constant costs decreased from $41.3 million in 1999/00 to $33.6 million in 2002/03. The DRG with the most variability in cost over time was that for opioid use which peaked in 1999/00 at $15.4 million, and then more than halved to a cost of $6.8 million in 2003/04.
Overall expenditures are greater among the 20–29 year age group (ranging from $13,130 in 1999/00 to $10,371 in 2003/04).
QLD had the highest expenditure per 1000 population across all years (range $8,265 per 1000 population in 1999/00 to $6,604 in 2003/04). The second highest expenditures varied between SA, WA and NSW.

b) Opioids
The main results for opioid-related separations include:

The total current costs for all opioid DRGs peaked in 1999/00 at $19.2 million.
The total constant costs of opioid-related separations decreased considerably between 1999/00 ($26.6 million) and 2001/02 ($15.2 million).
The DRG for opioid use was responsible for most of the costs, peaking at $15.4 million in 1999/00, then declining to $8 million in 2001/02.
The cost per 1000 population was greatest among the 20–29 year age group, with decreasing costs recorded among this group between 1999/00 and 2004/05.
New South Wales (NSW) had the highest expenditure per 1000 population for opioidrelated separations across all years.

c) Amphetamines
The main results for amphetamine-related separations include:

The ‘drug intoxication’ DRG consumed the most ‘current cost’ resources (47–60%).
The ‘constant costs’ increased from $7.8 million in 1999/00 to a peak of $11.3 million in 2001/02, which appears to be driven by the drug intoxication DRG.
The constant costs by age categories for amphetamine-related separations were greatest among the 20–29 year age group, ranging from $1507 per 1000 population in 1999/00 to $2013 in 2001/02.
QLD and WA had the highest expenditure per 1000 population for amphetaminerelated separations.

d) Cannabis
The main results for cannabis-related separations include:

The overall current costs each year for cannabis-related separations ranged between $5.0 million and $8.4 million.
Constant costs rose from $6.5 million in 1999/00 to $8.4 million in 2004/05 and was largely due to increases in drug intoxication DRG costs (from $3.7 million in 1999/00 to $5.8 million in 2001/02).
The constant costs for cannabis-related separations were greatest among the 20 to 29 year age group; however, the second largest expenditure per 1000 population varied between the 10 to 19 year and the 30 to 39 year age groups.
NSW, TAS and the NT had the highest expenditure on cannabis-related separations per 1000 population during the study period.

e) Cocaine
The main results for cocaine-related separations include:

The total constant costs for cocaine-related separations increased from 1999/00 ($331,386) to a peak of $691,789 in 2004/05.
The trend in the total constant costs for cocaine-related separations was driven largely by the other drug use DRG, which doubled between 1999/00 ($198,471) and 2001/02 ($400,840).

f) “Drug caused”
The main results for “drug caused” separations include:

The overall current costs for “drug caused” separations increased, from $7.7 million in 1999/00 to $11.6 million in 2004/05.
The total constant costs ranged between $10.0 million in 2000/01 and $11.6 million in 2004/05.
Low birth-weight newborns was the most costly diagnosis, and increased by 18% from $4.7 million in 1999/00 to $5.5 million in 2004/05.
Ante partum haemorrhage was one of the least expensive diagnoses over time however there was a proportional increase of approximately 30%, from $414,542 in 1999/00 to $544,731 in 2004/05.

g) Total costs and average cost per separation

Opioid-related separations were responsible for most of the expenditure across all years.
“Drug caused” separations contributed significantly to the total costs and were second only behind opioids.
Cannabis-related per separation costs were the most expensive, ranging from $2,896 to $3,412.
The average costs of “drug caused” separations were greater, particularly for pregnancy/neonatal (low birth-weight newborns and ante partum haemorrhage) separations, than those for the opioid-, amphetamine- and cocaine-related separations.

h) Average length of stay (ALOS)
The main results for ALOS include:

The ALOS for opioid-related separations in the drug intoxication DRG was considerably shorter (up to 40%) than the national average.
The ALOS observed for opioid-related separations in the opioid use DRG was generally longer than the national average (up to 55% longer).
Similar patterns were also observed for the other drug classes.

Discussion
The current costs for drug-related separations increased from $30.2 million to $35.7 million for all drug-related separations, which is in contrast to the constant costs (which will be used for the remainder of this discussion). These costs actually decreased over time by $4.2 million. Costs were highest for opioid-related separations followed by amphetamine-, cannabis- and cocaine-related separations. The total constant costs, when drug-related and “drug caused” costs were combined, were greater than previous estimates (Collins et al., 2007).

The change in costs among opioid-related separations in 2001/02 is consistent with a considerable decrease in the number of separations seen at this time (Roxburgh and Degenhardt, 2006) and evidence of a marked reduction in the availability of heroin in Australia (Day et al., 2003). This study showed an increase in costs related to amphetamine, cannabis and cocaine separations in 2001/02. Research has suggested that as a result of the reduction in heroin availability, a number of users “switched” use to other drugs, such as methamphetamine (Degenhardt and Day, 2004, Topp et al., 2002, Australian Institute of Health and Welfare, 2005a). This may explain the increasing costs seen among the other drug classes at this time.

The total costs for the “drug caused” separations in this study ranged from approximately $10 to $11.6 million, which is less than the annual expenditure on opioid-related separations but greater than annual costs for amphetamine-, cannabis- and cocaine-related separations. Of the “drug caused” diagnoses, costs for separations for low birth-weight babies were considerably higher than any of the other principal diagnoses. The average cost per separation was also considerably greater for a number of “drug caused” diagnoses than the average costs for separations with a drug-related principal diagnoses. This was particularly the case with separations for low birth-weight newborns and infective endocarditis, despite these separations occurring much less frequently. Therefore, a reduction in these separations would have a considerable decrease on the associated costs.

Costs were highest among the 20-29 year age group across all four drug classes, which is not surprising given population surveys reporting high prevalence of use among this age group (Australian Institute of Health and Welfare, 2005a). Generally, the 30–39 year age group was the second most expensive per 1000 population across drug classes. Costs among the 10 to 19 year age group for cannabis-related separations, however, were higher than or equal to those for the 30 to 39 year age group. According to the 2004 National Drug Strategy Household Survey, although prevalence of cannabis use wasn’t highest among 10 to 19 year olds, this group was more likely to report using a greater amount of cannabis per occasion of use (Australian Institute of Health and Welfare, 2005a).

Looking at jurisdictional differences, NSW had higher hospital costs per 1000 population for opioid- and cocaine-related separations compared to other jurisdictions. This is not surprising given that heroin and cocaine have historically been more readily available in NSW than other jurisdictions (Stafford et al., 2006a). The cost for amphetamine-related separations was highest in QLD and WA. Again, this result is not surprising given that among injecting drug users in WA, amphetamines were reported to be the drug most often injected in the month prior to interview between 2000 and 2005. There have also been
increases in the number of clandestine methamphetamine laboratories detected in QLD during this period (McKetin et al., 2005). The NT recorded the highest costs per 1000 population for cannabis-related separations which is also not surprising given that prevalence of cannabis use in the population is relatively higher in the NT than the other jurisdictions (Australian Institute of Health and Welfare, 2005b).

When drug-related and “drug caused” costs are combined, the costs estimates presented in this study are greater than previous estimates (Collins et al., 2007). However, these estimates are most likely to be conservative due to exclusion of other drugs and some principal diagnoses from analysis. In the most part, reducing presentations of these diagnoses could be avoided through effective early intervention and harm-reduction strategies, and therefore costs would be reduced. Future research needs to continue to monitor long-term trends in hospital costs for these drugs, as well as other drugs.

Citation: Riddell, S., Shanahan, M., Roxburgh, A., and Degenhardt, L. (2007) The cost of drug-related hospital stays in Australia, 1999 - 2005. Sydney: National Drug and Alcohol Research Centre.