The consequences of false positives in disease screening mainly refer to

The core of the false positive consequences of disease screening is The subject himself does not suffer from the target disease, but because the preliminary screening result is positive, the total unnecessary health damage, economic loss and psychological burden he endures subsequently。

Last year, when I was assisting with bowel cancer screening and follow-up at a community public health point, I met 48-year-old Zhang. He was usually strong enough to carry two bags of rice up to the fifth floor. But because of the free fecal occult blood screening test, he gave up smoking for half a month. He hid on the balcony and whispered to his wife, "What if it's really true?" Colon cancer can’t be cured, don’t drag the child down.” After the colonoscopy was done, it turned out that the internal hemorrhoids that had been suffered all year round were ruptured. It cost 1,200 yuan for the examination and medicine. After paying for the medical insurance, he paid more than 500 yuan. When he returned home, his wife stewed pork ribs for three days to calm his shock. He said that he was still scared when he saw the test paper showing hidden blood in the stool.

Don’t think that finding out everything is fine in the end means that the word “false alarm” can be dismissed easily. Some invasive follow-up examinations themselves bring health risks. I met a 32-year-old woman when I was reviewing cases before. The mammography target at the workplace reported a breast nodule of Category 4C. She was highly suspected of being malignant. I hurriedly performed a puncture, but the puncture needle pierced a peripheral blood vessel. The hematoma disappeared for less than half a month after the operation, and a shallow scar was left on her chest. The final pathological result was ordinary breast hyperplasia, and she did not even need to take medicine. This matter will make everyone angry, but it is useless to argue with the screening agency. Their operations are completely in compliance with the standards. After all, in order not to miss the real cancer, the sensitivity of the screening will be set relatively high, and false positives are the default "necessary price".

Oh, yes, the public health community has been arguing about this "necessary cost" for almost 20 years without coming to a conclusion. One group is traditional public health scholars, who believe that as long as the harm of a false positive is far lower than the risk of death and disability caused by missed diagnosis, it is cost-effective: after all, 100 false positives are just a false alarm, and in exchange for one cancer patient being discovered and cured early, it is worth it no matter what. But clinicians on the other side do not agree, especially urology doctors. When PSA (prostate-specific antigen) screening was popularized a few years ago, how many healthy men had their prostates removed due to false positives, and suffered a lot of postoperative urinary incontinence and sexual dysfunction. In the end, the pathology was completely benign. So later, the US Centers for Disease Control and Prevention directly changed the guidelines and did not recommend routine PSA screening for ordinary healthy men. They just felt that there was no need to let so many people suffer in vain.

In addition to the actual physical pain, my wallet was also injured. Take the currently popular low-dose CT screening for lung cancer as an example. If you report "ground glass nodules, follow-up recommended", you can't pretend you didn't see it, right? For the first two years, I had a CT scan every three months, which cost more than 300 yuan each time. In addition to the dozens of dollars each time I paid for a specialist appointment, I lost several thousand yuan in a year. In the last three years of follow-up, the nodule showed no change at all. The doctor said lightly, "It's just an old inflammatory lesion, don't worry about it." I met a little girl who was pregnant with her first child before. Tang Si reported high risk, and non-invasive DNA was still high risk. She cried and went for an amniocentesis. The final result was completely normal. She spent nearly 6,000 yuan. During that time, she had insomnia until the early morning every day, fearing that there would be something wrong with the baby. In the third trimester of pregnancy, she even needed sleeping pills prescribed by the doctor to fall asleep. This kind of emotional loss cannot be measured in money.

Of course, I have also met clinicians who hold the opposite view. When I was young, I worked in the oncology department of a tertiary hospital. In the past two years, I encountered false positive patients who came to the department and said that the hospital was deliberately scaring people to earn money for examination fees. However, he just received a 52-year-old smoker last month and actively requested to relax the screening threshold. Even if he did a few more tests, it didn't matter. In the end, he was actually screened for stage 1 lung cancer. He was cured after minimally invasive surgery and did not even need chemotherapy. He always said to me, "Would you rather 9 out of 10 people get a false alarm, or would you rather the 1 really sick person be missed and wait until it reaches the advanced stage and spend hundreds of thousands of dollars to cure it?" ”

In fact, there is no standard answer to this matter. Screening is like casting a net in the river to catch fish. The mesh is too small to miss the newly grown fish, but there are also a lot of broken branches and rotten plastics caught. These useless "junk" are false positives. You have to spend time and effort sorting, and you may even get scratched by the glass particles in the garbage. Different fish have different values. If you catch a wild large yellow croaker that costs tens of thousands of yuan per pound, it will be cost-effective to catch more garbage. If you catch a few small crucian carp, you will get a pile of garbage but the gain outweighs the loss. The same principle applies to screening: cancers such as lung cancer and colorectal cancer have a high mortality rate and are effective in early treatment. Everyone can accept a slightly higher false positive, but for ordinary benign disease screening, a too high false positive will simply cause trouble for everyone.

To put it bluntly, the consequences of false positives are never uniform statistics. They are spread to each specific person, including real physical pain, real money spent, and countless nights of tossing and sleeping. Nowadays, when many institutions promote screening, they only dare to say "early detection and early cure" and never mention the possibility of false positives. In fact, it will consume everyone's trust. When I choose a screening program for my elders, I will first check the approximate false positive rate of the program and whether the subsequent diagnosis steps will be traumatic, and then make a decision after weighing it carefully - after all, compared to "whether there is a disease", living a comfortable life is also very important.