A Korean comprehensive checkup is a bundle. The evidence inside it is not uniform

Ask whether a Korean comprehensive health checkup is worth having and the honest answer starts by rejecting the question. A 종합검진 is not a test. It is a package of tests sold together, and the reason the question is hard is that the package contains components whose evidence points in three different directions at once.

What the trials say about checkups as a whole#

The Cochrane review of general health checks, updated in 2019, pooled randomised trials comparing health checks against no health checks in adults not selected for disease or risk. It included 17 trials, 15 of which reported outcome data covering 251,891 participants.

The authors' conclusion was one sentence: general health checks are unlikely to be beneficial. The confidence interval on total mortality runs from 0.97 to 1.03 with no heterogeneity between trials, which is not an absence of evidence. It is evidence of absence, at a precision most clinical questions never reach.

And yet one Korean component clearly works#

Set against that, a nested case-control study within Korea's own National Cancer Screening Program, drawn from a cancer-free cohort of 16,584,283 people aged 40 and over. Compared with never being screened, ever being screened carried an odds ratio for gastric cancer death of 0.79. Split by method, the two halves of the programme separate completely.

Both findings are correct. They are not in tension because they are not answers to the same question. A trial of a general health check asks what happens when unselected adults are given a broad sweep of tests and follow-up. A study of gastric cancer screening asks what happens when a specific population with high disease incidence is offered a specific test for it. Korea has one of the world's highest gastric cancer burdens, which is the reason its national programme exists and the reason the trials — conducted mostly in Western populations, mostly before endoscopy was routine — do not settle the Korean case.

The third category: tests that carry documented harm#

The private comprehensive checkup is where the bundle stops resembling the national programme. An analysis of 190 comprehensive examination programmes advertised by ten university hospitals in Seoul found that 132 of them — 69.5 percent — included computed tomography, at an average of 1.4 scans.

Cost correlated with dose at r = 0.812. The single most important determinant of which band a programme fell into was whether it included positron emission tomography combined with computed tomography. Programmes with the same stated purpose differed in dose by as much as 2.1 times depending on the hospital.

How to read a package that contains all three#

Korea's national programme contains components with mortality evidence behind them. Faecal immunochemical testing was associated with an odds ratio of 0.74 for colorectal cancer death in a cohort of 5,944,540 people. Mammography was associated with a breast cancer mortality rate ratio of 0.43 in a cohort of 8,300,682 women. Upper endoscopy halves the odds of dying of gastric cancer, with a dose-response across repeat screens.

It also contains upper gastrointestinal series, which on the same national data does nothing. And the private packages built around the national programme add imaging whose dose reaches 18 to 24 times the annual dose limit for a member of the public, sold to people with no symptoms.

The useful question is therefore not whether to have a checkup. It is which tests are in this particular package, and which of the three categories each one falls into. That is answerable, item by item, and the rest of this series does it.