'Physician Trust' Tied to PSA Testing

Nick Mulcahy

February 09, 2018

SAN FRANCISCO — The level of trust a man has in his physician is "strongly associated" with the decision of whether to undergo prostate-specific antigen (PSA) screening, according to a new study of US attitudes and behaviors presented here at the Genitourinary Cancers Symposium (GUCS) 2018.

Interestingly, a man's degree of trust in cancer information found on the Internet was not significantly associated with getting the test,  when multiple variables were considered.

"If you trust your physician a lot, you are more likely to discuss PSA screening as well as receive it," Zachary Klaassen, MD, a urologist at the University of Toronto, Ontario, Canada.

He spoke to Medscape Medical News while standing in front of his poster at the symposium.

Dr Klaassen is a member of the famed urology group in Toronto, which is led by active surveillance pioneer and PSA screening champion Laurence Klotz, MD. They see patients at the Princess Margaret Hospital.

The PSA test triggers a lot of feelings in men, said Dr Klaassen: "I have a colleague who says that PSA stands for 'prostate- or patient-specific anxiety.'"

"We wanted to assess factors that may lead patients to get PSA screening or not," he continued. They especially wanted to address the variable of physician trust because shared decision making is becoming "more and more important." To do so, the team had to use US data. "Physician trust is not in many databases," Dr Klaassen explained.

Physician trust is not in many databases. Dr Zachary Klaassen


But it is in the Health Information National Trends Survey (HINTS), a survey of people living in the United States. So the team performed a cross-sectional study using data from 2011 to 2014.

The primary exposure was degree of trust in cancer information from a participant's physician; the secondary exposure was the same thing, but for cancer information obtained from the Internet. The primary outcome was patient-reported receipt of PSA screening.

There were 5069 eligible men in HINTS. Most trusted their doctors: that is, 71.1% (n = 3606) reported trusting cancer information from their physician "a lot," while 23.4% (n = 1186) trusted it "some." Only small fractions trusted "a little" (4.3%; n = 219) or "not at all" (1.1%; n = 58).

About half of the total group received PSA screening (52.4%; n = 2655). The degree of trust in cancer information from the physician was strongly associated with the likelihood of receiving PSA screening.

Among the men who reported "a lot" of trust, 54.9% underwent screening, as did 48.6% of the "some" trust group, 38.4% of the "little" trust group, and 27.6% of the "not at all" trust group (trend P < .0001).

Sumanta K. Pal, MD, urologic oncologist at City of Hope Cancer Center in Duarte California, and an American Society of Clinical Oncology expert, suggested the findings make sense.

"It's somewhat implicit: The more a patient trusts a physician, the greater the likelihood that they will follow recommendations, which may include PSA screening," Dr Pal told Medscape Medical News. The relationship between physician trust and the presence of PSA screening (or not) "should probably go hand in hand," he added.

However, Cara Litvin, MD, an internist at the Medical University of South Carolina in Charleston, found the results hard to interpret without knowing how the risks and benefits are being conveyed to patients.

Dr Litvin has also researched the PSA decision process. She told Medscape Medical News that she has found that physicians' "inherent biases" are reflected in how they describe PSA; doctors who believe in the value of PSA "tend to have more patients who undergo screening, perhaps because they trust their physicians' recommendations."

In the new study, the degree to which men trusted the Internet was also tied to having received PSA screening (P = .005), but with an insignificant trend (P = .07), reported the study authors in their abstract.

However, the findings about the Internet did not hold up when multiple variables were considered.

The authors reported that after multivariable adjustment, these significant results persisted for degree of trust in cancer information from a physician; the reference figure was "a lot." For "some," the odds ratio (OR) was 0.80 (95% confidence interval [CI], 0.66 - 0.97); for "a little," the OR was 0.61 (95% CI, 0.41 - 0.90); and for "not at all," the OR was 0.33 (95% CI 0.15 - 0.73).

But the same did not hold true, after multivariable adjustment, for trust in cancer information from the Internet.

The new study also contained a host of other findings, including "the more money you make, the more likely you are to get a PSA test," said Dr Klaassen. But he acknowledged that this result may be confounded by healthcare access.

Dr Klaassen has financial ties to BioSyent. Other study authors have multiple ties to pharmaceutical companies, including ones with prostate cancer products. Dr Pal has financial ties to Eisai, Ipsen, Astellas, Medivation, Bristol-Myers Squibb, Exelixis, Genentech, Myriad Pharmaceuticals, Aveo, Novartis, and Pfizer.

Genitourinary Cancers Symposium (GUCS) 2018. Abstract 13. Presented February 8, 2018.

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