Laser treatment for glaucoma

Gus Gazzard and colleagues1Gazzard G Konstantakopoulou E Garway-Heath D et al.Selective laser trabeculoplasty versus eye drops for first-line treatment of ocular hypertension and glaucoma (LiGHT): a multicentre randomised controlled trial.Lancet. 2019; 393: 1505-1516Summary Full Text Full Text PDF PubMed Scopus (236) Google Scholar compared initial selective laser trabeculoplasty with eye drops in patients with open angle glaucoma or ocular hypertension. The primary outcome was health-related quality of life, assessed by EQ-5D. The mean EQ-5D scores were 0·89 (SD 0·18) for the eye drops group and 0·90 (SD 0·16) for the laser group after 36 months. Any differences in these scores are impossible to assess and giving these results to three significant figures would make more sense. In the original publication, discrepancies between the text and the tables and figures made it difficult to determine whether the comparisons between treatments were based purely on outcome at 36 months or whether change from baseline for each group was compared. I would expect that the change from baseline would be compared, but the paucity of precision made it hard to tell. However, in the corrected version, published on July 6, 2020, the presentation suggests that a simple comparison has been made at 36 months. A comparison of the change from baseline would seem more appropriate, and possibly significant because the laser group began the study with a poorer status (EQ-5D score 0·91 vs 0·92). To be fair, Gazzard and colleagues1Gazzard G Konstantakopoulou E Garway-Heath D et al.Selective laser trabeculoplasty versus eye drops for first-line treatment of ocular hypertension and glaucoma (LiGHT): a multicentre randomised controlled trial.Lancet. 2019; 393: 1505-1516Summary Full Text Full Text PDF PubMed Scopus (236) Google Scholar do not use their non-significant so-called superiority of selective laser trabeculoplasty as the basis for a cost–benefit analysis (otherwise, with the decreased costs, selective laser trabeculoplasty would be dominant), but limit themselves to estimating cost savings. These estimates alone might be enough to convince advisory committees, such as the National Institute for Health and Care Excellence, with a presumption of non-inferiority. However, such phrases as “mean incremental QALY [quality-adjusted life-year] of 0·011”, which refer to non-significant gains, even though correctly accompanied by limits, might well have helped prompt the media to subsequently comment that the laser treatment is “not only more effective and safer, but should also save the NHS [National Health Service] £1·5m a year”.2McKie R 15-minute laser is best treatment for glaucoma patients, says study.https://www.theguardian.com/society/2019/mar/09/15-minute-laser-treatment-best-for-glaucoma-patientsDate: March 9, 2019Date accessed: May 13, 2020Google Scholar Of course, my concerns would be altered if, indeed, analysis of change from baseline shows a significant difference, as would the main thrust of the paper. I declare no competing interests. Selective laser trabeculoplasty versus eye drops for first-line treatment of ocular hypertension and glaucoma (LiGHT): a multicentre randomised controlled trialSelective laser trabeculoplasty should be offered as a first-line treatment for open angle glaucoma and ocular hypertension, supporting a change in clinical practice. Full-Text PDF Open AccessLaser treatment for glaucoma – Authors' replyWe thank John Larkin for his comments on our Article.1 He expresses his interest in seeing the EQ-5D scores reported to three significant figures. Although this request is not unreasonable, we feel that it is unnecessary. We feel that there is an obvious absence of a clinically important difference between the two treatment groups. The sample size was based on detecting a difference of 0·05 and three significant figures are not required to see this difference; figure 2 shows that the differences with time never reach clinical significance. Full-Text PDF