One in six adults screened in Korea had haemorrhoidal disease, and childbirth is what separates women from men

The prevalence of haemorrhoidal disease is usually quoted as 7 to 14 percent, a range wide enough that the range itself was the finding — the studies behind it were small, and most of them counted people who had come to a doctor to complain. This one counted 194,620 people who had come for a health check, and found more.

Who was counted#

The participants were not patients. They were healthy adults who completed a screening examination including colonoscopy between 2011 and 2017, which means the condition was found by looking rather than reported by someone motivated to mention it. That cuts both ways, and both directions are worth holding. It avoids the distortion of a clinic sample, where every participant by definition had a symptom bad enough to act on. It also counts disease in people who had no complaint at all, so the 16.6 percent is not a count of people who need treatment.

The sex difference is a parity difference#

Women had the higher prevalence — 17.2 against 16.3 percent — and at this sample size the gap was statistically solid. Splitting the women by whether they had given birth dissolves the simple version of it. Against men as the reference, parous women were more likely to have the condition, with an adjusted odds ratio of 1.06, and nulliparous women were less likely, at 0.92.

So "haemorrhoids are more common in women" is true of the population and misleading about the mechanism. What is more common is haemorrhoidal disease after childbirth. On this data a woman who has not given birth carries slightly lower prevalence than a man of the same age, which is the opposite of the received summary.

What on the list can actually be changed#

Older age, female sex, smoking, being overweight and being hypertensive were each independently associated with the presence of the condition. Two of those five are modifiable. That is close to the whole practical content of a cross-sectional design: it can say what travels with a condition and it cannot say what causes it, because exposure and outcome were measured on the same day.

Hypertension is the entry worth watching, and not because the association is large. It is the first sign in this data that haemorrhoidal disease may sit alongside systemic and cardiovascular disease rather than being a purely local complaint — a question two later Korean cohorts took up directly, with follow-up long enough to measure outcomes instead of co-occurrence.