Measuring medicine prices in Peru: validation of key aspects of WHO/HAI survey methodology.
OBJECTIVE
To assess the possibility of bias due to the limited target list and geographic sampling of the World Health Organization (WHO)/Health Action International (HAI) Medicine Prices and Availability survey used in more than 70 rapid sample surveys since 2001.


METHODS
A survey was conducted in Peru in 2005 using an expanded sample of medicine outlets, including remote areas. Comprehensive data were gathered on medicines in three therapeutic classes to assess the adequacy of WHO/HAI's target medicines list and the focus on only two product versions. WHO/HAI median retail prices were compared with average wholesale prices from global pharmaceutical sales data supplier IMS Health.


RESULTS
No significant differences were found in overall availability or prices of target list medicines by retail location. The comprehensive survey of angiotensin-converting enzyme inhibitor, anti-diabetic, and anti-ulcer products revealed that some treatments not on the target list were costlier for patients and more likely to be unavailable, particularly in remote areas. WHO/HAI retail prices and IMS wholesale prices were strongly correlated for higher priced products, and weakly correlated for lower priced products (which had higher estimated retailer markups).


CONCLUSIONS
The WHO/HAI survey approach strikes an appropriate balance between modest research costs and optimal information for policy. Focusing on commonly used medicines yields sufficient and valid results. Surveyors elsewhere should consider the limits of the survey data as well as any local circumstances, such as scarcity, that may call for extra field efforts.
Madden
Jeanne M
JM
Department of Population Medicine, Harvard Medical School, Harvard Pilgrim Health Care Institute, United States of America, Boston, MA 02215, USA. jeanne_ madden@hphc.org
Meza
Edson
E
Ewen
Margaret
M
Laing
Richard O
RO
Stephens
Peter
P
Ross-Degnan
Dennis
D
D000806:Angiotensin-Converting Enzyme Inhibitors / Q000191:economics / Q000600:supply & distribution; D000890:Anti-Infective Agents / Q000191:economics / Q000600:supply & distribution; D000897:Anti-Ulcer Agents / Q000191:economics / Q000600:supply & distribution; D000927:Anticonvulsants / Q000191:economics / Q000600:supply & distribution; D003625:Data Collection / Q000379:methods*; D016568:Drugs, Generic / Q000191:economics / Q000600:supply & distribution; D005252:Fees, Pharmaceutical / Q000706:statistics & numerical data*; D007004:Hypoglycemic Agents / Q000191:economics / Q000600:supply & distribution; D010568:Peru; D004364:Pharmaceutical Preparations / Q000191:economics* / Q000600:supply & distribution; D010594:Pharmacies / Q000145:classification / Q000191:economics / Q000706:statistics & numerical data; D017150:Public Sector / Q000191:economics; D012494:Sampling Studies; D014944:World Health Organization
D000806:Angiotensin-Converting Enzyme Inhibitors; D000890:Anti-Infective Agents; D000897:Anti-Ulcer Agents; D000927:Anticonvulsants; D016568:Drugs, Generic; D007004:Hypoglycemic Agents; D004364:Pharmaceutical Preparations