Objective. To establish the reliability/validity of an 18-item test of patients’ medical data interpretation skills.Design. Survey with retest after 2 weeks.Subjects. 178 people recruited from advertisements in local newspapers, an outpatient clinic, and a hospital open house.Results. The percentage of correct answers to individual items ranged from 20% to 87%, and medical data interpretation test scores (on a 0- 100 scale) were normally distributed (median 61.1, mean 61.0, range 6-94). Reliability was good (test-retest correlation = 0.67, Cronbach’s alpha = 0.71). Construct validity was supported in several ways. Higher scores were found among people with highest versus lowest numeracy (71 v. 36, P < 0.001), highest quantitative literacy (65 v. 28, P < 0.001), and highest education (69 v. 42, P = 0.004). Scores for 15 physician experts also completing the survey were significantly higher than participants with other postgraduate degrees (mean score 89 v. 69, P < 0.001).Conclusion. The medical data interpretation test is a reliable and valid measure of the ability to interpret medical statistics.
Committee on Quality of Health Care in America. Institute of Medicine. Crossing the Quality Chasm: A New Health System for the 21st Century. Washington, DC: National Academy Press; 2001.
2.
Department of Veterans Affairs. VHA Notice 99-02. Shared decision making. June 15, 1999. Available from: http://www.va.gov/putl/direc/health/notice/n9902.pdf. Accessed April 8, 2004.
3.
Sheridan S, Harris R, Woolf S.Shared decision making about screening and chemoprevention: a suggested approach from the US Preventive Services Task Force. Am J Prev Med. 2004;26(1):56-66.
4.
Nease RF, Brooks WB. Patient desire for information and decision making in health care decisions: the autonomy preference index and the health opinion survey. J Gen Intern Med. 1995;10:593-600.
5.
Deber R, Kraetschmer N, Irvine J.What role do patients wish to play in treatment decision making?Arch Intern Med. 1996;156:1414-1420.
6.
Jones R, Pearson J, McGregor S, et al.Cross sectional survey of patients’ satisfaction with information about cancer. BMJ. 1999;319:1247-1248.
7.
Laine C, Davidoff F, Lewis C, et al.Important elements of out-patient care: a comparison of patients’ and physicians’ opinions. Ann Intern Med. 1996;125:640-645.
8.
Degner L, Kristjanson L, Bowman D, et al.Information needs and decisional preferences in women with breast cancer. JAMA. 1997;277:1485-1492.
9.
MedlinePlus. Trusted Health Information for You. A Service of the National Library of Medicine and the National Institutes of Health. Available from: http://www.nlm.nih.gov/medlineplus/
10.
Kirsch IS, Jungeblut A, Jenkins L, Kolstad A.Adult Literacy in America. Washington, DC: National Center for Education Statistics; 1993.
11.
Schwartz LM, Woloshin S, Black WC, Welch HG. The role of numeracy in understanding the benefit of screening mammography. Ann Intern Med. 1997;127:966-972.
12.
Baker DW, Williams MV, Parker RM, Gazmararian JA, Nurss J.Development of a brief test to measure functional health literacy. Patient Educ Counsel. 1999;38:33-42.
13.
Lipkus IM, Samsa G, Rimer BK. General performance on a numeracy scale among highly educated samples. Med Decis Making. 2001;21:37-44.
14.
Feinstein A.Clinimetrics. New Haven, CT: Yale University Press; 1987.
