Purpose of positive predictive value table

I am baffled by Table 1 (cancer symptom positive predictive values [PPVs]) in the Oncology Briefs article by Dr Wilkinson in the April issue of Canadian Family Physician.¹

All physicians are trained to investigate new-onset constipation, rectal bleeding, cough, and other “red flags” in patients older than 50 years of age. So, I am unsure of the purpose of Table 1. Is there a cutoff below which investigation is unwarranted?

For example, I investigate patients older than 50 with a new unremitting cough (PPV = 0.40) more than I would investigate those with new nocturia (PPV = 2.2). Even new hematuria alarms me more than new nocturia.

Dyspnea only has a PPV of 0.66, but I pull out all the stops for patients with new dyspnea.

Perhaps the author could explain the purpose of including Table 1 in this article.

I now spend about a third of my time in home-based palliative care. Many of my dying patients feel guilty (if they believe they have neglected early symptoms) or have anger toward their family physicians (if they believe their family physicians neglected early symptoms). Retrospectively, it is easy to recall early symptoms that “should have” prompted investigation. However, my office practice is swamped with a plethora of vague symptoms, and I am always concerned about balancing underinvestigation with overinvestigation.

I suppose I would like Table 1 to be more helpful in showing “where to draw the line.” Thank you.

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