Study design, materials and methods
A published probabilistic Markov model was adapted for Australia to compare lifetime costs and quality-adjusted life years for Australians with SCI, based on intermittent use of hydrophilic coated catheters (HCIC) compared with uncoated catheters (UC). Health states included three renal and three urinary UTI states. The base case analysis was from the Australian healthcare perspective, including healthcare costs and benefits. A supplementary analysis from the societal perspective that incorporated costs from lost productivity was also conducted. Sensitivity analyses were conducted to test the sensitivity of the model to key clinical and cost input parameters.
The model predicts that a 48 year old SCI patient will survive an additional 0.82 years using HCIC compared with UCs, at an incremental cost of $35,942.
Lifetime UTI events were reduced by 10% with HCIC use. This equates to approximately $286,000,000 saving to the healthcare system purely considering a reduction in community treated UTI in the SCI population of Australia over their lifetime but not considering the added cost of utilising a hydrophilic catheter. The incremental cost-effectiveness ratio (ICER) of $49,297 was below the threshold of $50,000 to $60,000 cost per QALY informally interpreted as showing cost-effectiveness of new medical technologies and pharmaceuticals in Australia. When the societal perspective was taken, HCIC use produced superior clinical outcomes at a lower total cost compared with UCs.
Interpretation of results
The model predicts a 48-year-old SCI patient using HCIC would live an additional 12.93 years, compared with an additional 12.11 years with use of UC, an incremental gain of 0.82 life years. An additional 5.96 QALYs were gained with HCIC use compared with 5.23 with use of UC a QALY gain of 0.73. Four fewer UTI events were experienced in a lifetime, a reduction from 37 UTIs with UCs to 33 using HCICs.
The incremental cost of using HCIC, compared with using UC was $35,942. The resultant incremental cost-effectiveness ratio (ICER; incremental cost/incremental QALYs) was $49,297.
The supplemental analysis that included the impact of productivity loss during a UTI demonstrates that use of HCIC is dominant, compared with UC, due to the reduced costs and higher benefits seen compared with UC. A sensitivity analysis, with 30% reduced workforce participation rates compared with the total Australian population, was also dominant due to reduced costs and increased benefits with HCICs compared with UCs.
Key cost variables that impact cost-effectiveness, including cost per catheter and number of catheters per day were investigated in sensitivity analyses. When HCIC and UC prices were changed from the most used brands weighted by distribution method (i.e. price and sales volumes via websites or government subsidised programs) to an average of the least expensive HCIC and UC prices listed on two sales websites, the analysis resulted in an ICER of $,9645 (cost/QALY), with a QALY gain of 0.73 and a total lifetime cost increase of $7,032 per patient.
The impact of varying clinical variables was also investigated in sensitivity analyses, including inputting the 95% confidence intervals for the effectiveness of HCIC vs UC from the meta-analysis. The ICER (cost/QALY) was improved to $26,574 when the lower 95% CI was used (risk ratio 0.75) and reduced to $93,153 when the upper 95% CI (risk ratio 0.94) was used. Increasing and decreasing the baseline risk of UTI by 5% resulted in an ICER (cost/QALY) of $42,920 and $56,504, respectively. Thus, both the baseline risk of UTI and the effectiveness of HCICs over UCs are important clinical variables that impact the cost-effectiveness of the 2 catheter types. The utility benefit of HCICs was varied from the base case value of 0.028 to both 0 and 0.05; as expected the model is highly sensitive to this variable.
The impact of increasing the discount rate for costs and benefits from 1.5% to 3.0% (as utilised for cost-effectiveness considerations by the Australian Pharmaceutical Benefits Advisory Committee - PBAC) resulted in only a small impact on the ICER (cost/QALY), with an increase from $49,297 to $49,586 observed.
Important clinical improvements seen with use of HCICs included an average gain of 0.82 life-years per person or 0.73 QALYs per person with SCI and a mean reduction of 4 UTI events per lifetime, compared with use of UCs.
To put this in context, the Department of Health QALY assessment of antiretroviral treatment for HIV patients demonstrated a QALY gain of 0.76 for patients on treatment.
Utilising the mean cost of a UTI responding to initial treatment in the community of $6344.38/UTI, a conservative estimate of lifetime cost savings for SCI patients in Australia (Peter New, estimating the incidence and prevalence of SCI in Australia 2015) is valued at $286,765,976.00
UTI was the most common complication leading to rehospitalisation in the 2 years following traumatic SCI at an average cost per admission of $19,617 ± $26,985 (in 2012 Australian dollars); hence reducing UTI incidence will have a significant impact on both an individual’s quality of life and on total healthcare costs. This analysis showed that the use of HCICs, with their higher unit price but reduced overall treatment cost could improve healthcare resource allocation by reducing costly, common UTI events. The sensitivity of the analysis with regard to UTI rate is important. Thus the cost and QALY savings would be more significant in patients who are at a higher baseline risk of UTI. The need for this type of analysis to help identify treatment approaches associated with both cost savings and improved outcomes in bladder management practice has recently been identified.
While there are no explicit willingness-to-pay thresholds for Pharmaceutical Benefits Scheme (PBS) listing decisions published by the Australian Pharmaceutical Benefits Advisory Committee (PBAC), an ICER threshold of $50,00 to $60,000/QALY have been suggested as being potentially acceptable. Our study demonstrates the ICER for the base case analysis of $49,297 is lower than the suggested threshold range supporting the argument for cost effectiveness for HCIC for SCI patients in the Australian setting. The reduced healthcare costs and higher effectiveness (QALY gains) demonstrate significant productivity benefits with HCIC use compared to UC in this setting.
When the cost-effectiveness analysis included productivity impacts, HCIC was found to provide greater benefit while also reducing total healthcare and societal costs, supporting cost savings with use of HCICs despite their comparatively greater acquisition cost, further supporting the need for easier and more cost effective access to HCIC in this population.
The range of results seen with the base case, and this sensitivity analysis using the cheapest HCIC and UC in the market, show that regardless of preferred HCIC type, the use of HCICs broadly are cost-effective, while allowing individuals choice of HCIC and associated features (e.g. size, portability, comfort, readiness and ease of use, suitable packaging etc.) to suit their clinical and lifestyle needs. This would also be a strong argument to facilitate better pricing of catheters from industry.