(Natural News) The PHQ-9 questionnaire has been used by doctors for twenty years. It contains only nine questions, and was developed by funding from major drug corporation Pfizer, a report on DailyMail.co.uk said. The company supplies commonly prescribed depression and anxiety medications, including Venlafaxine and Sertraline.

Through the questionnaire, patients are asked to rate their experiences of depression symptoms such as poor appetite, low energy, erratic sleep, and poor concentration levels, based on how often they’ve felt it — whether “on several days”, “nearly every day”, or the like. They are given scores based on their answers, and the total is then checked against a depression severity scale that goes from not depressed to severely depressed.

Many critics have found that the questionnaire lowers the standards for depression. They also criticized how doctors do not spend more time in conducting appropriate psychiatric interviews, saying that this could lead to a clinical depression diagnosis for a patient who is simply undergoing a stressful period in his or her life.