| Verified against primary record | |
| Advertising rule | A percentage success rate must not be given without making clear the actual number of patients treated[1] |
|---|---|
| Regulator on small gaps | Small differences between clinics’ rates often do not reflect any real difference in performance[2] |
| Case mix | Comparing unadjusted average scores between providers can be misleading[3] |
| Records read | A regulator’s clinic pages, two enforcement documents, two adjudications and two outcome methodologies, 9 October 2026 |
| Provider-supplied | |
| A claim held unsubstantiated | 99 per cent successful results, advertised by a hair transplant provider[4] |
| Bands apply only to the rows beneath them. No clinic success rate is reproduced in this entry as a measure of performance. | |
Treatment success rates are the most prominent numbers in medical travel marketing and the least comparable. Four things have to be fixed before two rates mean the same thing: what counts as success, what the denominator is, what mix of patients produced it, and over what period it was measured. Published clinic rates typically specify none of them.
The denominator decides the number
The clearest demonstration available comes from a statutory regulator that publishes two different success measures for the same clinical activity and explains both. Births per embryo transferred is calculated using the number of births, with twins or triplets counted as one birth, divided by the number of embryos transferred, shown as a percentage, in a clinic over 12 months. Births per egg collection uses as its denominator the number of egg collection procedures that took place in a clinic over 12 months, and is shown as a percentage over a two-year period.[2]
The two answer different questions, and the regulator says so: the first is not usually used to show outcomes over more than one treatment cycle, while the second can be used to show outcomes from all embryo transfers from the same egg collection.[2] Their inclusions differ too, with one excluding pre-implantation testing and donor-egg cycles where the other includes testing and excludes donor eggs, and both are split by patient age band.
Identical clinical work therefore yields two legitimate and materially different percentages. A clinic free to choose which to publish, and not required to say which it chose, can present the more flattering one without stating anything false.
Case mix, and the reporting period
Even with a fixed denominator, a raw comparison between providers is uninformative. England’s national outcome programme states that comparing unadjusted average scores between providers can be misleading, because the patient profiles that one provider treats may be different to the patient profile at another provider, and that adjustment takes into account the fact that some patients can be predicted to experience better or worse outcomes.[3] The mechanics are set out in risk adjustment in hospital comparisons.
The reporting period is the fourth variable, and it changes the answer most for implants and devices. An arthroplasty registry publishing comparative prosthesis performance states that the benchmark standard used to assess superiority and non-inferiority performance at 10 years is 4.4 per cent, with superiority applying when the upper confidence interval is less than or equal to that benchmark.[5] A success rate quoted at discharge, at six weeks and at ten years are three different quantities, and only the last says anything about whether an implant lasted.
What regulators require, and what they have found
Two United Kingdom regulators have addressed success-rate advertising directly in one sector. An enforcement notice states that clinics must not advertise success rates as a percentage without making clear the actual number of patients treated, must not give undue prominence to the results of a subset of patients whose results are good, and must indicate exactly which metrics are being used to demonstrate success.[1] A joint letter from the competition and advertising regulators identifies the problem as clinics advertising success rate claims, including superiority claims, without clearly identifying the basis of the claims, making it difficult for patients to meaningfully compare between clinics, and asks for unsubstantiated superiority claims to be removed.[6]
Those rules have been applied to medical travel providers. On 11 October 2023 the advertising regulator upheld complaints against two Turkish hair transplant providers advertising to United Kingdom audiences. Of a claim of 99 per cent successful results it recorded that it received no evidence from the advertiser to substantiate the efficacy of the procedure in achieving the claimed results.[4] Of a second provider’s claim to deliver defined and strong hair in just one day, it found that the advertising had exaggerated the effectiveness of the hair transplant, again having received no substantiating evidence.[7]
These are the only adjudicated success-rate claims by medical travel providers located for this entry. Both went against the advertiser on the simple ground that no evidence was supplied.
Why small differences should be ignored
The same fertility regulator publishes guidance that applies to any clinic league table. Small differences between clinics’ rates often do not reflect any real difference in performance, and readers are told not to read into differences of a few percentage points above or below the national average. It publishes a reliability range, described as showing how confident it is that a clinic will repeat its success rate in the future, and suppresses small counts, noting where a number is fewer than five and has been removed to avoid the risk of identifying patients.[2]
No numeric clinic rates are reproduced in this entry. The statistics tables returned placeholder values when read for this site, so only the definitional and interpretive text was verified.
Five questions for any published rate
What event counts as success, defined clinically. What is the denominator, and does it include patients who did not complete treatment. How many patients does the percentage rest on. Over what period after the procedure was it measured. And has it been adjusted for case mix, or is it a raw figure from a self-selected caseload. A rate that cannot answer the first three is not a measurement, and under the enforcement notice above it would not be compliant advertising in at least one jurisdiction.
See also
- Complication rates in medical tourism, the same denominator problem in reverse
- Risk adjustment in hospital comparisons, how case mix is corrected for
- Clinical outcomes in medical tourism, what success would be measured against
- Hair transplant tourism, the sector in which both adjudications arose
References
- Committee of Advertising Practice. Enforcement notice, advertising of fertility treatments. Compliance deadline November 2021; no issue date printed on the document. Verified against primary record: enforcement notice opened and read. Retrieved 9 October 2026.
- Human Fertilisation and Embryology Authority. Choose a clinic, clinic record. Last reviewed 15 July 2025. Verified against primary record: measure definitions, reporting periods, reliability range and suppression rules read; no numeric success rate was retrievable. Retrieved 9 October 2026.
- NHS England. The National Patient Reported Outcome Measures programme. Version 3, August 2018. Verified against primary record: case-mix adjustment section opened and read. Retrieved 9 October 2026.
- Advertising Standards Authority. Ruling on Get DHI Hair Clinic trading as GETDHI. Reference A23-1199875, 11 October 2023. Verified against primary record: published adjudication opened and read. The 99 per cent figure is the advertiser’s own claim and was found unsubstantiated. Retrieved 9 October 2026.
- Australian Orthopaedic Association National Joint Replacement Registry. Comparative prostheses performance, supplementary report. 2022 annual report, data period 1 September 1999 to 31 December 2021. Verified against primary record: benchmark standard and assessment rule read. Retrieved 9 October 2026.
- Competition and Markets Authority and Advertising Standards Authority. Complying with consumer law and the advertising codes in the fertility sector, a joint letter. 23 September 2022. Verified against primary record: joint letter opened and read. Retrieved 9 October 2026.
- Advertising Standards Authority. Ruling on Dakik Saglik Medikal Turizm A.S. trading as Clinicexpert Hospital. Reference A23-1199876, 11 October 2023. Verified against primary record: published adjudication opened and read. Retrieved 9 October 2026.
Sourcing note: the enforcement notice, the regulator’s clinic pages, the joint letter, the two adjudications and the two outcome methodologies were opened and read on 9 October 2026. No clinic success rate is reproduced as a measure of performance, and the only percentage quoted is an advertiser’s own claim that a regulator found unsubstantiated. Numeric rates on the fertility regulator’s clinic pages returned placeholder values when read for this entry, so only definitional and interpretive text is cited from them. The two adjudications are the only ones against medical travel providers on success-rate grounds located here, which is a search result rather than a complete record.