The consequences of false positives in disease screening mainly refer to

The core consequences of false positive disease screening refer to a series of negative impacts such as unnecessary health damage, economic costs, psychological impact, and associated misallocation of medical resources due to abnormally positive screening results for subjects who did not originally suffer from the target disease.

When I volunteered for early screening in community health last year, I met 52-year-old Aunt Zhang. The unit’s physical examination included low-dose chest CT. The report said “ground glass nodule in the upper lobe of the right lung, highly suspected of malignancy.” She squatted in the hospital corridor with the report and cried for half an hour. After that, she went to three hospitals in the next half month. Hospital A, I did two contrast-enhanced CTs, one PET-CT, and finally a lung puncture to determine that it was an old calcification lesion left by tuberculosis more than ten years ago. I spent more than 20,000 yuan and lost 8 pounds. After that, for more than half a year, I had to get a CT scan whenever I had a cough. I always felt like I had "cancer".

This is actually the most typical false positive injury. Many people think that everything will be fine after getting the final "excluded diagnosis", but they don't know that some injuries have already been caused from the moment the positive result comes out. For example, some invasive further examinations have inherent risks: lung puncture may cause pneumothorax and bleeding, and gastroscopic biopsy may cause damage to the gastrointestinal mucosa. There are even extreme cases where false positive results directly promote unnecessary surgeries. In the past two years, there has been discussion about the over-promotion of thyroid screening. Many subjects with ordinary inflammatory nodules had part or even all of their thyroids removed because of the strict interpretation of screening results, and had to take thyroid hormone drugs to maintain metabolism for the rest of their lives.

Regarding the tolerance of false positives, there have always been two completely different views in the industry. Most scholars in the field of public health epidemiology believe that false positives are the price that must be borne by early screening. After all, as long as a few more early-stage cancer patients can be screened out, even if there are ten or hundreds more false positive subjects, it will be profitable from the perspective of population survival rate. ； But most doctors in clinical ethics and general practice don’t see it this way. A director of general practice I know said, “The probability of falling into a group is one in a thousand, but it is 100% trouble if it falls on a specific person. It is obvious that the false positive rate can be reduced by strictly controlling screening indications, so why should ordinary people bear unnecessary costs? ”

When I talked with imaging doctors before, they said that the sensitivity and specificity of screening are like a seesaw. When the sensitivity is fully stretched, it is like a fishing net with extremely small mesh. It will not miss the fish, but it will also catch a bunch of aquatic plants and stones. These "aquatic plants and stones" are false positives. Think about it, many physical examination packages now prescribe low-dose CT to young people in their 20s who do not smoke and have no family history of lung cancer, regardless of age or medical history. The prevalence of lung cancer in this group of people is less than one in 10,000. Even if the false positive rate of CT is only 1%, for every real patient detected, 100 false positive people will suffer. It is not cost-effective no matter how you calculate it.

Many people ignore the hidden psychological damage. This kind of damage has no bills or wounds, but is the most difficult to resolve. I previously visited a doctor in the Department of Psychosomatic Medicine and met a 28-year-old girl. The cervical cancer screening TCT reported "high-grade squamous intraepithelial lesions". She was so scared that she quit her job and even wrote a suicide note. In the end, the biopsy was just ordinary inflammation. After that, she did not dare to have sex for more than a year. She always felt that she was "dirty and there was something wrong with her." It took half a year of psychological counseling to recover.

Looking at the entire medical system, large-scale false positives will also cause a run on medical resources. Last year, a city in the south conducted a large-scale primary screening for gastric cancer. The sensitivity of the test kit was adjusted too high, and 12,000 positive cases were screened out at once. All local hospitals' appointments for digestive endoscopy were scheduled three months later. Several high-risk patients with a family history of gastric cancer and gastric ulcers themselves were not scheduled for further examinations. In the end, they had to travel across the city to seek medical treatment, which was a waste of time.

When I recommend screening programs to people I consult, I never recommend a "full set of early screenings." I will always ask about age, family history, past medical history, and living habits first, and calculate "how likely you are to get this disease." For example, a 30-year-old woman with no family history of breast cancer does not need to do a mammogram at all. A breast ultrasound is enough. The false positive rate of mammography for young people with dense breasts is ridiculously high, and she is just looking for trouble for herself.

In fact, many people's understanding of screening is a bit extreme now. They either think that "it's always right to check more, and you can rest assured if you find out", or they simply don't check anything after hearing that there are false positives. In fact, it is not that black and white at all. Instead of worrying about whether a false positive will catch you, it is better to find a reliable doctor to ask whether you are the target group of this screening project before doing the screening. It is much more reliable than blindly following the trend and buying sky-high price physical examination packages.