New guidance has recently been published on how patients who take the medicine hydroxychloroquine should be screened to prevent eye problems. Hydroxychloroquine can cause damage to the back of the eye (retina). Although this problem is rare, if it is not spotted early and the medicine stopped, it can cause blindness. The new guidance recommends specialist tests done in hospital eye clinics. This had not been recommended before. In order to follow the guidance, a lot more tests and appointments than previously will be needed in hospital eye clinics but there has been no previous estimate of how many more.
We will use the records of prescriptions from the CPRD to find out how many people are taking hydroxychloroquine. We will use this number to estimate the number of people in the UK who are taking hydroxychloroquine. We will also use the records of prescriptions to find out how long people continue to take hydroxychloroquine, and use this to work out many additional hospital eye clinic tests and appointments are needed.
This study will provide information for planning hospital eye services which is much needed by the commissioners of healthcare in the UK.
Background: The Royal College of Ophthalmologists published new guidance in February 2018 on screening for people taking hydroxychloroquine. The new guidance recommends specialist tests undertaken in hospital eye clinics; whereas previous guidance did not. Eye tests are recommended at baseline, 5 years after treatment initiation and annually thereafter. The guideline was published without providing an estimate of the number of people it will affect, and the effect on already over-stretched eye services.
Aims: We aim to estimate the number of people in the UK currently receiving hydroxychloroquine for any indication, and the length of time they continue to take this for, and to use this to provide estimates of the number of additional eye clinic appointments implementing the guideline will require.
Methods: We will identify all people in CPRD Gold who have ever been prescribed hydroxychloroquine. We will estimate the contemporary point prevalence of current hydroxychloroquine using the number currently taking either drug as the numerator and the whole CPRD population as the denominator. We will apply these estimates to the population of the UK to estimate the number of people in the UK currently taking hydroxychloroquine.
We will use prescription data to estimate the length of time each person continues to take hydroxychloroquine. We will use Kaplan-Meier methods to estimate the proportion of people continuing to take hydroxychloroquine at time-points annually 1-20 years after drug initiation. We will use this data to estimate the number of people in the UK requiring hospital eye tests.
Impact: This study will provide information which commissioners of hospital eye services in the UK need to plan how best to implement the recommendations of the guideline.
1) The number of people in the CPRD taking hydroxychloroquine.
2) The length of time that people prescribed hydroxychloroquine continue on the drug.
Fiona Pearce - Chief Investigator - University of Nottingham
Fiona Pearce - Corresponding Applicant - University of Nottingham
Anthony King - Collaborator - University of Nottingham
Matthew Grainge - Collaborator - University of Nottingham
Peter Lanyon - Collaborator - Nottingham University Hospitals
Richard Hubbard - Collaborator - University of Nottingham