Using 'willingness to pay' to elicit patients' values for health

Document Sample
Using 'willingness to pay' to elicit patients' values for health Powered By Docstoc
					Contingent valuation and public
 health: eliciting values from
    patients and the public
         PAPER PRESENTED
    TO IDEP- GREQAM WORKSHOP
          By Cam Donaldson
         23RD-24TH JUNE 2003
“Political economy has to take as the measure of utility of an
  object the maximum sacrifice which each consumer would
  be willing to make in order to acquire the object....the only
  real utility is that which people are willing to pay for.”

Jules Dupuit (1844)
   What I am not doing today…
• Discrete choice/conjoint analysis
• Willingness to accept
• Conventional validity studies:
  – e.g. payment vehicles

Mostly about enhancing the validity of WTP
 studies with respect to relevance to
 decision-makers.
                       Outline
• Why WTP in health?
• Using the values in decision making
        – Uptake of WTP studies
        – Patients and the public
        – Distributional issues

• Progress in eliciting values from patients
• Progress in eliciting values from the
  community?
           What are we valuing?

                Productivity



Resource
inputs          Healthy time          UTILITY


                How resources are
                used, e.g. process,
                location
           WTP: why we need it

•   strength of preference
•   can compare different „goods‟
•   pulls together several factors
•   „beyond health‟
•   more in line with theory? Less restrictive on:
           – Mode of sacrifice
           – Evaluation „space‟
           – Separability
              Uptake of WTP
• Do hypothetical questions give hypothetical
  answers?
        – Comparisons to revealed preference
        – Scope
        – Still developing (CV/SG)

• Unethical to use in decision making?
• Perceptions and guidelines
• General problem with economics?
            Whose values?

                           Whose values?
                           Patients Public
            Private          (1)     (2)
Nature of
good        Collectively     (3)     (4)
            financed
               USING WTP DATA:
               four main scenarios
(1) Patients; private good
      If WTP > cost, implement
(2) Public; private good
      If WTP > cost, implement
(3) Patients; collective good
      Three possibilities
(4) Public; collective good
      Need WTP and cost data for alternative uses of
      resources
     WTP AND DISTRIBUTION OF INCOME:
           ‘CURRENT’ THINKING

“..the validity of this approach rests upon some important Paretian
    assumptions; one being that individuals are the best judges of their
    own welfare, another being that the current distribution of income is
    appropriate.”
[O‟Brien B and Drummond MF (1994) Statistical versus quantitative significance in the
   socioeconomic evaluation of medicines. PharmacoEconomics, 5: 389-398.]


“Cost-benefit analysis‟s primary valuation method is willingness to
  pay(authors‟ emphasis) (WTP), an approach whose difficulty lies in its
  intrinsic favouring of the programs and diseases of the affluent over
  those of the poor”
[Gold M et al. (1996) Effectiveness in Health and Medicine. New York, Oxford Univ Press,
   pXXII]
      Distribution: what to do?
• Universal problem: QALYs have it too
• Leave values unweighted? (Pauly)
• Decision-making view (Currie et al., Little
  etc)
• Sensitivity tests (Boardman et al.,
  Donaldson)
        – Direction of preference
        – Strength of preference within income groups
        – Sensitivity of end results to different weights
         „WTP for own care‟
• ask patients to value their own treatment
• example: pre-natal CF testing:
  – both parents have to test positive
  – disclosure versus non-disclosure
  – 127 out of 176 in trial responded to WTP
    questionnaire
      RESULTS FROM CF SCREENING STUDY




(1)     About £21!
(2)     No difference between groups.


This result has been shown in other studies.
     CF follow up: ‘WTP for each’


• make respondents aware of alternatives
• reference point theory
• example: CF follow up
  – non-trial sample of 450 pregnant women asked about
    WTP for each method
 RESULTS FROM CF FOLLOW UP

(1)   Lower response rate.

(2)   61% preferred disclosure; 27% preferred non-
      disclosure.

(3)   Problems with validity.
                 MATCHING OF
             PREFERENCES AND WTP

                  Is WTPD > or < WTPND?
Pref       Less            Equal             Greater    Total
Disc       61 (17%)        99 (28%)          62 (17%)   222 (62%)
Non-disc   78 (22%)        16 (4%)           94 (26%)
None       21 (6%)         22 (6%)           1          44 (12%)

N.B. 90 people did not respond to this question.
              MARGINAL APPROACH

Give the respondent details of each alternative (i.e. “existing” and
   “alternative” care) and ask them:
   -     which they prefer;
   -     what is the maximum amount they would be willing to pay to
   have their preferred rather than their less-preferred option.

This has been done in studies of:
   -     management of miscarriage
   -     intra-partum care (postal; open-ended)
   -     parents‟ views of services for children (interview; bidding).
STUDY OF CHILD HEALTH SERVICES

(1)   82 parents interviewed (out of 300 asked
      to participate)
(2)   Each parent was asked one WTP question
      about each of three pairwise choices:
      • inpatient stay versus day case for tonsillectomy
      • hospital-based versus local clinics for bedwetting
      • school health service to focus on all children or those with
        special needs.
     RESULTS FROM STUDY OF
     CHILD HEALTH SERVICES
                                     WTP for:
                       Day case                 I/p stay
Mean                    £56                        £43
(95% CI)             (£28, £84)                 (£22, £63)

Median                   £45                      £27.50
(25th,75th %iles)   (£0.125, £100)               (£0, £50)

Total WTP               £1570                     £1119
          WTP AND DISTRIBUTION

Data on preferences allow us to analyse whether richer people
  tend to prefer one option and, therefore, whether mean (or
  median) WTP for that option is a result of greater
  “purchasing power” (i.e. ability to pay) as well as
  willingness to pay.

Therefore, analyse preferences by:
  -    income
  -    social class
    Distribution of preferences [and mean
     WTP] for surgery by income group


                               Income (£s per week):
          <£100    £100-£150 £150-£230     £230-£350   >£350
Inpatient    4         2         8              5         5
           [£25]     [£75]      [£44]         [£56]     [£25]

Day case     5         2          8            4          6
           [£32]     [£50]      [£86]        [£77]      [£43]
              USING THE RESULTS

(1)Assuming options are mutually exclusive, other things
   (including cost) being equal, the option to be implemented
   would be that preferred by whichever group could
   compensate the other and still remain better off.

(2)Where other things (e.g. cost) are not equal, if the option
   with greater WTP (and hence utility) also has a greater
   cost, the decision maker then has to decide whether this
   extra cost is worth incurring.
       BROADER PRIORITY SETTING

150 in Northern Norway were asked their maximum WTP for three public
   sector health care programmes:

   -    a helicopter ambulance
   -    80 more elective heart operations per annum;
   -    250 more hip replacements per annum.


                  WTP RESULTS (NOK; n=143)
              Helicopter             Hearts            Hips
              316                    306               232
       Why WTP is important
• The highest valued QALYs are for the
  helicopter, which might reflect a preference
  for the „rule of rescue‟.
• Life saving is more highly valued than the
  same QALY gain from life extension and
  life improvement
• If the results are valid!
     Problems with this method
• Rank orderings do not match WTP orderings
• „Size of the good‟ problems.
Hence, EuroWill, to examine:
• Can different countries do it?
• Various methodological issues (size of good,
  closed-ended vs payment scale, informational
  effects, marginal approach, econometric issues)
   Mean WTP ($PPPGDP, 1999) using
         standard approach
                 Hearts                    Cancer
Norway     100 operations = $44   300 procedures =   $49

Portugal   150 operations = $24   300 procedures =   $27

Denmark    3 to 1 month = $73     Not applicable

UK         100 operations = $78   150 procedures =   $81

France     250 operations = $52   Improved outcome = $47

Ireland    100 operations = $59   200 procedures =   $69
      WHERE NOW FOR WTP?
        Conduct of studies
•   Do not use „WTP for own care‟
•   Open-ended questions are problematic
•   Use some form of “payment vehicle”
•   Postal questionnaires require careful design
•   Tests for effects of income/class are feasible
•   „Marginal approach‟ has potential for
    choices between close substitutes
     WHERE NOW FOR WTP?
    Recommendations for research
• Compare payment vehicles
• More testing of the „marginal approach‟
• Extend to broader priority setting contexts
  – EUROWILL
• External validity/strategic bias
            Positive outlook
THE ECONOMIST OF OLD
“Knows the price of everything and the value of
  nothing.”

THE MODERN ECONOMIST
“Knows the price, and is some way towards knowing
  the value, of health care at the margin”.
                    Or....
...MAUREEN LIPMAN‟S MOTTO

“Life‟s like a questionnaire. You didn‟t ask to
  be sent it, can‟t think what the answers are,
  but might as well fill it in and hope it gets a
  laugh.”

				
DOCUMENT INFO
Shared By:
Categories:
Tags:
Stats:
views:5
posted:4/9/2011
language:English
pages:30