Value of information in the osteoarthritis setting: cost effectiveness of COX-2 selective inhibitors, traditional NSAIDs and proton pump inhibitors.
BACKGROUND
Recent National Institute for Health and Clinical Excellence (NICE) guidance recommended that when traditional NSAIDs or cyclo-oxygenase (COX)-2 selective inhibitors are used by people with osteoarthritis (OA), they should be prescribed along with a proton pump inhibitor (PPI). However, specific recommendations about the type of NSAID or COX-2 could not be made due to high levels of uncertainty in the economic evaluation.


OBJECTIVE
To investigate the value of obtaining further evidence to inform the economic evaluation of NSAIDs, COX-2s and PPIs for people with OA.


METHODS
An economic evaluation with an expected value of perfect information (EVPI) analysis was conducted, using a Markov model with data identified from a systematic review. The base-case model used adverse event data from the three largest randomized trials of COX-2 inhibitors, and we repeated the analysis using observational adverse event data. The model was run for a hypothetical population of people with OA, and subgroup analyses were conducted for people with raised gastrointestinal (GI) and cardiovascular (CV) risk. The EVPI was based upon the OA population in England - approximately 2.8 million people. Of these, 50% were assumed to use NSAIDs or COX-2 selective inhibitors for 3 months per year and 56% of these were assumed to be patients with raised GI and CV risk.


RESULTS
The value of further information for this decision problem was very high. Population-level EVPI was £85.1 million in the low-risk group and £179.5 million in the high-risk group (2007-8 values). Expected value of partial perfect information (EVPPI) analysis showed that the groups of parameters for which further evidence was likely to be of most value were CV adverse event risks and all adverse event rates associated with the specific drugs celecoxib and ibuprofen. The value of perfect information remained high even when observational adverse event data were used.


CONCLUSIONS
There is a very high value associated with obtaining further information on uncertain parameters for the economic evaluation of NSAIDs, COX-2 selective inhibitors and PPIs for people with OA. Obtaining further randomized or observational information on CV risks is likely to be particularly cost effective.
Health Economics and Decision Science, School of Health and Related Research, University of Sheffield, Sheffield, UK. n.latimer@sheffield.ac.uk
Nicholas
N
Latimer
Joanne
J
Lord
Robert L
RL
Grant
Rachel
R
O'Mahony
John
J
Dickson
Philip G
PG
Conaghan
D000894:Anti-Inflammatory Agents, Non-Steroidal / Q000191:economics* / Q000627:therapeutic use; D003362:Cost-Benefit Analysis; D052246:Cyclooxygenase 2 Inhibitors / Q000009:adverse effects / Q000191:economics* / Q000627:therapeutic use; D006801:Humans; D033181:Information Dissemination; D010003:Osteoarthritis / Q000188:drug therapy* / Q000191:economics* / Q000378:metabolism; D054328:Proton Pump Inhibitors / Q000191:economics* / Q000627:therapeutic use
D000894:Anti-Inflammatory Agents, Non-Steroidal; D052246:Cyclooxygenase 2 Inhibitors; D054328:Proton Pump Inhibitors