Rating Dyspnea and Pain: "No" is Not Always "Zero".

Nurses routinely assess pain in hospitalized patients; similar assessment of dyspnea is increasing. Most nurses start with a yes-no question when assessing pain or dyspnea; many record "no" as a zero rating, skipping the rating scale. We tested the hypothesis that recording "no" answers as "zero" fails to detect the symptoms that would have been detected with a rating scale.