Monitoreo del depósito de relaves

Resources used

The economic analysis was based upon 102 patients over a three month follow up

period . The evaluation adopted the perspective of the health care system .All resource

items associated with the interventions , with post operative stay and community care

received over the follow-up period were identified , and the volumes of these resources

used by each patient were recorded .

The resources used fell into three broad categories:

1. Theatre costs - these consisted of capital equipment, theatre overheads including

2. Hotel costs - taking into account ward overheads and ward capital costs , length of

stay and post-operative consumables and morbidity .

3. Community costs - including visits to the GP , practice nurse and hospital out­

patients, and home visits from the district nurse .

Valuation of resources

Once the volume of resources used by each patient had been calculated , the

opportunity cost of these resources (that is , the opportunity forgone to commit these

resources to some other alternative use) was measured in terms of the unit costs of

each resource item based on 1994/ 1995 market prices including (where chargeable)

value added tax (VAT). These unit costs were then applied to the resource volumes to

obtain a total cost per patient .Because the time from randomisation to follow-up was

only three months , it was necessary to apply a discount rate to costs However, the

costs of capital equipment were computed in present value terms , as described below.

All cost data are reported as mean values , differences in means and associated 95%

confidence intervals .

The cost of laser consumables was based on the usage of the SLT MD60

Neodymium : YAG contact laser with an estimated ten year lifespan (personal

communication Kontron Instruments , Watford , Herts., UK ) , and the MTRL 10 6

mm sapphire tipped probe . Fibres were used a maximum of three times , and tips a

maximum of 6 times .

The equivalent annual cost of the laser equipment was calculated by depreciating the

capital cost over a ten year period , and assuming an opportunity cost of 5% per

capital funds been invested in some other way .This ‘opportunity cost’ of the capital

cost is effectively the discount rate which is applied in all the economic evaluations

when costs or benefits are spread over time The cost of twice yearly servicing of the

laser has also been included .

Health service facilities used by the patients , capital costs of building space , and

overheads for both operating theatre facilities and ward or ‘hotel’ stay were valued

using costs generated by the ‘SAPPS’ (Speciality and Procedures Pricing System ) at

the Churchill Hospital. Included in these overheads for both ward and operating

theatre , were building and staff costs as well as a proportion of the costs for

portering , catering, training etc.; that is , all the facilities necessary to run the clinical

service These overheads were allocated to patients on the basis of length of stay or

theatre operating time . Theatre staff costs were attained using the mid-point on the

relevant salary scale with an additional 13% added for employers’ costs .

The costs of practice nurse attendance following discharge were obtained by assuming

a ten minute consultation with an F grade nurse , taking the mid point on the salary

scale, and the employers costs This is in accordance with the current practice of the

Oxfordshire Family Health Service Authority. The cost of a consultation with a general

practitioner was costed from government expenditure plans for 1992 /1993 as

documented in a Department of Health report, and updated to 1994/1995 prices using

the Health Specific Price Index .

The cost of retreating patients with a repeat prostatectomy was estimated using the

mean values for resource use in the relevant arm of the trial. It is assumed that the

variation about the mean in terms of resource use in each group is the same in retreated

Indirect costs such as loss of income borne by the patients were not an important

factor in this age group , supporting the decision to adopt a health care system

perspective in the economic evaluation .

Sensitivity Analysis

The cost of consumable equipment for contact laser prostatectomy may vary in the

future as may the recurrence of benign prostatic enlargement in both trial arms .A

sensitivity analysis has therefore been performed to examine the implications of making

different assumptions about laser consumable costs , and re-operation rates .

The mean difference in cost between laser and TURP plotted against varying laser re­

operation rates , using different assumptions on TURP re-operation rate at one

year The mean difference in the cost between the two procedures was also plotted

against a percentage decrease in the cost of laser consumables (100% being the

current list price) . For each assumption of variation in laser consumable price , the

mean cost for the procedure was re-calculated from the initial stages of the financial

analysis .

Finally, the relationship between laser re-operation rate and mean difference in cost

between the two procedures was examined assuming a hospital stay of one night and

two district nurse visits This assumption allows for catheter removal at home if the

Chapter 3 -Results

Accurate data were available on 148 patients that were randomised ; losses prior to

randomisation being shown in table 1 .

Exclusion criteria Numbers

Previous prostate surgery 22 Known prostatic carcinoma 21

Refusal o f consent 5

Poor English / dementia 7

Other 21

Table 1 - Losses prior to randomisation

Losses included under the title ‘other’ included those with neurological conditions but

predominantly reflected a period when the laser was not available , or malfunctioned

requiring repair ,or when the trial co-ordinator was not available .

72 patients were treated with contact laser prostatectomy, while 76 received TURP.

The mean age in the TURP group was 70 years (standard deviation [SD] 8),

compared to 69 years (SD 8) in the laser group .