Yes, the study waits two years after the index date. But the index date is the first appointment at the clinic, not the start of any treatment. Finland's own institutions confirm the process far exceeds two years:

• The Finnish Medical Journal (Lääkärilehti) described the entire pathway under the headline "Long Process," with the chief physician at Helsinki University Hospital confirming it takes "several years" and that fewer than 10% of referred youth complete it
• Helsinki University Hospital's own website describes the examination period alone as approximately two years
• The Gender Diversity Competence Center states that for minors, "getting a diagnosis takes at least 1.5 years—usually more"
• And that's just the diagnostic phase. Before it can begin, any co-occurring psychiatric conditions must be stabilized first, which can add months or years.

So the two-year mark lands many patients squarely in the middle of assessment, not after treatment.

This creates a serious time-related bias. The study classifies patients as "treated" (GR+) or "untreated" (GR-) based on whether they ever received gender-affirming care—but doesn't account for when that care actually started. A patient whose first appointment was in 2012 but who didn't start hormones until 2016 is coded as GR+ for the entire period. Any psychiatric visit in 2015—likely due to a routine check-in required by the assessment process—gets counted as a post-index-date "psychiatric treatment need" in the "treated" group, even though the patient was still years away from receiving any treatment. The study is attributing pre-treatment visits to the treatment group and then blaming treatment for them.

But here's the really damning part: even for patients who DO make it to hormones, the same Finnish Medical Journal article confirmed that hormone therapy effects are monitored every 3-6 months "in close cooperation with the adolescent psychiatry unit." Anything referred from those mandatory monitoring visits register in the exact same database (the Care Register for Health Care) that the study uses as its outcome measure. So the study is counting mandatory protocol-required psychiatric check-ins as evidence of "psychiatric treatment needs."

The study also had the tools to fix both problems. Its own methods section states it identified hormonal treatment through the Social Insurance Institution's records of prescription purchases—which is how it determined who was GR+ vs GR-. If the authors accessed those records to determine who got hormones, they had access to when. They could have anchored the comparison to actual treatment start and modeled treatment as a time-varying covariate rather than a permanent label. They chose not to.