Caution needed when examining certificate of vision impairment rates: the new public health indicator

Abstract

Sir, Caution needed when examining certificate of vision impairment rates: the new public health indicatorWe read with interest the paper by Rostron and McKibbin 1 suggesting a possible fall in certificate of vision impairment (CVI) due to age-related macular degeneration (ARMD) in Leeds. It demonstrates the potential value in exploring variation in CVI rates across the country. As readers are aware the CVI is a public health indicator for vision in the newly launched Public Health Outcomes Framework, 2 so there is added interest in these figures. We feel that it is important to highlight that while CVI figures accurately describe new registrations in social service departments, it is currently unclear how this relates to disease burden as not everyone eligible for certification is certified. 3 Bunce et al 4 found that patients who require treatment for their sight impairment are almost three times less likely to be certified than those in whom treatment is not indicated. The fact that there are now new treatments for wet ARMD may mean less certifications not because of less need for social care support, but because certification can be seen to be done when no further treatment is available. Caution is needed if comparing BD8 certifications with CVI certifications, which are why the recent report by the Chief Medical Officer included CVI figures for 2007/8 as baseline. 5 When the BD8 was replaced by the CVI between 2003 and 2006, new registrations for sight impairment fell by 4000 for reasons which remain unclear, but which pre-dated widespread use of anti-VEGF drugs. This makes temporal comparisons difficult, which is why we believe focus should be on data collected from 2007 and beyond. The data reported for the period 2008 and 2010 in the paper suggests a relatively stable number of CVI registrations due to ARMD with a rise in the numbers in 2010 at a time of widespread adoption of ranibizumab therapy in the NHS. Though the incidence is reported per million population per year in the paper, it may be better to report this as a rate per million population older than 65 years of age (i.e., the at-risk population rather than total population) as in the Public Health Outcome Framework. Conflict of interestThe authors declare no conflict of interest.

Is preventable sight loss truly preventable? An exploration of a public health indicator for sight loss due to age-related macular degeneration in England

“…The findings in this paper of IRs of AMD CVI registrations being more common in women and increasing with age for all types of AMD is in keeping with the existing literature [ 3 , 24 , 25 ]. AMD is shown to be more prevalent in elderly age groups and age is the most strongly associated risk factor [ 2 , 10 , 12 , 14 , 15 ].…”

Area deprivation, individual socioeconomic status and low vision in the EPIC-Norfolk Eye Study

“…Certification is not an accurate reflection of prevalence of VI,37 and our study has provided a more accurate picture of the relationship between area deprivation and visual function.…”

“…A recent study examining the correlation between IMD and certification of VI found no association, 25 although the authors also found an 11-fold variation in registration rates, indicating differences in registration practices and data collection may have resulted in significant measurement error. Certification is not an accurate reflection of prevalence of VI, 37 and our study has provided a more accurate picture of the relationship between area deprivation and visual function.…”

Agreement between ophthalmologists and optometrists in the certification of vision impairment

“…An additional role of the certificate of vision impairment is the collection of epidemiological information about the incidence and causes of certifiable sight loss in the UK [4,5]. Whilst the number of certificates issued in the UK accurately reflects those registered with social services as having vision impairment [6], it does not represent all individuals living with sight loss. Indeed, it is estimated that up to 51% of those eligible for certification are not certified [7][8][9] and the incidence of certification varies across geographical locations [10].…”