FRIDAY, Oct. 17 (HealthDay News) -- Many patients misunderstand the written questions American doctors have them answer before physical exams, a finding that calls into question the usefulness of these screening tools, new reports say.

Two studies, presented earlier this year at the 2008 Clinical Congress of the American College of Surgeons, found that lower-than-expected literacy levels among patients and a failure to understand basic numerical measurements hurt the validity of the questionnaire results. A third study, though, found promise in using computer programs to "speak" the questions to patients.

The studies, by researchers at the Emory University School of Medicine in Atlanta, noted shocking literacy issues. In the first, it was found that of 300 men at an inner-city hospital -- average age 61 and average reading level of fourth grade -- only one in six understood all seven questions used for in the International Prostate Symptom Score (IPSS). In all, only 38 percent of patients understood more than half the questions, such as: "During the last month or so, how often have you had to push or strain to urinate?"

"Possibly the most worrisome thing was the number of patients who thought they understood this test -- the most commonly used instrument in urology worldwide -- but did not," Dr. Viraj A. Master, an assistant professor of urology at Emory, said in a news release issued by the American College of Surgeons.

The study also found that many patients were not capable of discussing numbers and quantities, such as rating something on a scale of one to 10 or saying whether a symptom occurred "a third of the time."

In the second study, less than a third of 266 patients -- average age of 58 -- understood numbers and quantities well enough to pass a three-question Woloshin-Schwartz numeracy quiz. The quiz asked questions such as "Imagine that we flip a coin 1,000 times. What is your best guess about how many times the coin will come up heads in 1,000 flips?" (Answer: 500 times).

Most respondents were considered "innumerate," with 33 percent answering only one question correctly and 35 percent having no correct answers.

"Even after controlling for age, race, homelessness, English as a second language, income, and a host of other variables -- including educational level -- numeracy was shown to be an independent predictor of misunderstanding," Master said. "Being innumerate, in addition to being illiterate, results in high levels of misunderstanding that severely limit access to appropriate health care for millions of patients."

Master and his colleagues tried adding pictures to their screening tests to help illustrate the concept being discussed, but this did not improve understanding in a randomized prospective trial. However, in a third study, when the team designed a computer program in which a figure speaks to the patient, asking the IPSS questions, the level of understanding increased dramatically.