PREVALENCE AND PREDICTION OF DRUG-INDUCED PHOTOSENSITIVITY

Abstract

Abstract Background: The prevalence of drug-induced photosensitivity (DIP), and the clinical and photobiological profile of affected patients, is poorly understood. There is limited information on the extent or prevalence of DIP in the UK. Determining which drugs may induce DIP and whether certain patients are more susceptible, would be a significant step in patient management. Aims: To determine the prevalence of DIP both within photosensitive patients diagnosed in the Photobiology Unit (Salford Royal NHS Foundation Trust) between 2000 and 2016 and the wider community at outpatients’ clinics (Salford Royal NHS Foundation Trust). Further, to characterise the clinical and photobiological features of DIP patients and identifying the key culprit drugs. Methods: Study one: a retrospective review of patients who received a diagnosis of DIP in the Photobiology Unit. Clinical history, phototest results and impact on the quality of life (QoL) associated with DIP were collated. Study two: A questionnaire-based study at Salford Royal outpatients’ clinics was undertaken. Information on medicine usage and the effects of sun exposure was collected. Respondents taking potential photosensitising medication and describing a temporally associated atypical sun exposure-response were identified as cases of probable DIP. Results: The prevalence of DIP for all patients attending the photobiology unit was 5.4% (122 of 2,243). Key culprit drugs were quinine (11.5%), diuretics (10.7%), antifungals (9.8%), and proton pump inhibitors (9.8%). Quality of life (QoL) index over the past week (and year) was classified as moderately impaired in 24% (41% year), very largely impaired in 22% (31% year) and extremely largely impaired in 3.7% (17.2% year). Of the 986 individuals approached in study two, 531 (53.8%) agreed to participate of whom 89.4% (475) were taking 1416 medications, 50.4% being potential photosensitisers. Sun responses were reported by 112 participants, of which a temporal association with the commencement of a potentially photosensitising drug(s) could be identified in ten individuals (2.1%). These ten cases of probable DIP were taking 15 different potential photosensitisers including: statins (6), proton pump inhibitor, omeprazole (5), anti-hypertensives (4) and anti-depressants (4); however, when normalised to the number of participants taking the drug, azathioprine (66.7%), quinine (33.3%) indapamide (25%) and diltiazem (20%) were the drugs most commonly associated with probable DIP. Due to the low numbers of probable DIP identified, further characterisation of participants at risk of DIP was not possible. Conclusion: The prevalence of DIP and its impact on patients’ QoL highlighted the importance of this adverse drug reaction and the need to establish effective strategies for diagnosing and providing appropriate management. Key photosensitisers were identified, including the developing issue of DIP reactions to PPI’s. Phototesting, particularly broadband UVA provocation testing, was recognised as an essential diagnostic tool. The questionnaire has the potential to quickly screen for potential cases of DIP, having identified ten probable cases. However, standard phototesting would be required to make a confirmed diagnosis and validate the questionnaire findings.

Date of Award	1 Aug 2021
Original language	English
Awarding Institution	The University of Manchester
Supervisor	Rachel Watson (Supervisor) & Mark Farrar (Supervisor)