A qualitative study of knowledge, behaviour and attitudes regarding vitamin D acquisition among patients with photosensitivity disorders

Cutaneous exposure to sunlight is a major source of vitamin D. Individuals with photosensitivity disorders have symptoms provoked by sunlight and may not achieve the brief sunlight exposures that convey vitamin D acquisition.

then hepatic hydroxylation to 25-hydoxyvitamin D (25(OH)D; calcidiol), the main circulating form and accepted indicator of vitamin D status. Further hydroxylation in the kidney produces the active hormone 1,25-dihydroxyvitamin D (1,25(OH) 2 D; calcitriol), which binds the vitamin D receptor in target cells to mediate its action.
Vitamin D deficiency, defined as a circulating 25(OH)D concentration of less than 25 nmol/L (10 ng/mL), is prevalent in the UK, affecting as much as 39% of adults in the winter months when UVB levels are negligible at UK latitudes. 2,5 Low vitamin D status can cause rickets in children and osteomalacia in adults and children, while associations between low vitamin D status and several malignant and autoimmune disorders have been reported. 6,7 National guidance on sunlight exposure in the UK allows for brief exposures to achieve adequate vitamin D status while avoiding excessive exposure to reduce risk of skin cancer. 8 In 2016, the Scientific Advisory Committee on Nutrition (SACN) revised its guidance on oral vitamin D intake to recommend 10 µg daily during the winter months for those aged 1 and over in order to avoid vitamin D deficiency, and year-round for "at-risk" groups including those aged 65 and over, those with darker skin and those with minimal sunlight exposure due to cultural or medical reasons. 6 Photosensitivity disorders are characterised by abnormal skin reactions to low levels of ultraviolet radiation (UVR) and/or visible light. 9 Overall, photosensitivity disorders affect a large proportion of the population with the most common disorder, polymorphic light eruption (PLE), estimated to affect around 18% of the Northern European population. 10 Photosensitivity disorders present with a range of symptoms and clinical features, in which some disorders appear rapidly upon sunlight exposure such as in solar urticaria (SU) and erythropoietic protoporphyria (EPP), or after a delay of several hours such as in PLE.
The mainstay of treatment of photosensitivity disorders is photoprotection with broad-spectrum sunscreens, protective clothing and sun avoidance. 9 These photoprotective behaviours result in reduced sun exposure in patients with photosensitive disorders and increased risk of vitamin D deficiency. Previous studies have shown that patients with a range of photosensitivity disorders have levels of 25(OH)D which can be up to 18%-25% lower than healthy individuals. [11][12][13] However, previously they were no more likely to take vitamin D supplements than healthy adults despite spending less time outdoors in the summer months. 14 Thus, the aim of this study was to explore the current knowledge, behaviours and attitudes towards acquiring vitamin D among individuals with photosensitivity disorders, including conditions that manifest rapidly (SU, EPP) and after a delay (PLE) following sunlight exposure.

| PATIENTS AND ME THODS
This was a qualitative study performed in 2014-2015 that used focus group research methodology [15][16][17]  Patients participated in focus groups comprising individuals with the same photosensitivity disorder with individual group sizes approximating those suggested to be optimal for focus group research. 16 The format and topic guide were based on those used previously for different ethnicity groups 18 and patients with skin cancer. 19 Discussions lasted 45-60 minutes, were facilitated by a trained researcher and were digitally recorded. Following a brief introduction to the study, the facilitator utilised a topic guide to as-

| Vitamin D knowledge
Nearly all patients had some knowledge of vitamin D, and this had been obtained from a variety of sources. Some patients reported that their own diagnosis of vitamin D deficiency was their cue to finding out more information. Contact with secondary or tertiary care clinicians, particularly at the Salford Royal Hospital Photobiology Unit, was the most commonly cited source:
There was particularly good awareness among all patient groups that the sun is an important source of vitamin D, but the quality and depth of this knowledge was variable. While many patients were aware that food could be a source of vitamin D, there was a lack of knowledge of specific vitamin D-rich foods. Many patients were unaware that fruits and vegetables were a poor source of vitamin D:

| Attitudes
All patients were willing to take oral vitamin D supplements if required but some voiced concerns including the taste of supplements, lack of monitoring while actively taking supplements, intolerance or side effects, cost, and a perceived risk of overdose: Q: Would you be willing to take vitamin D supplements?
PLE8: "I am happy to take supplements if it is a once a day tablet." SU2: "I would be willing to take supplements if it is going to make a difference." PLE1: "I can't tolerate the tablets, I can't digest them." SU2: "I would be happy to take them if it's something that is going to be monitored." SU4: "If you take too much, does it affect your liver?" At the end of each focus group discussion, patients were invited to give their thoughts on how to increase awareness of vitamin D including its function and sources. Several strategies were suggested but in particular educating clinicians, especially GPs, was popular ( Figure 1).
Furthermore, they stated that attempts to improve awareness needed to be targeted and unambiguous: SU3: "Targeting information better would work rather than general information for the whole population. You need to target those who are more at risk, for example people who stay out of the sun like us." The focus group is an effective research methodology that is commonly used to explore the factors that influence individuals' beliefs, attitudes and behaviours. 16,17 We limited potential bias and increased the reliability of analysis through digital recording of each focus group session and by having these recordings transcribed by an independent researcher. The number of patients involved in our study (n = 19) was appropriate, with individual group sizes approximating those suggested to be optimal for focus group research. 16 The gender balance of patients represented the fact that there is a higher prevalence of these photosensitivity conditions in females.
Our finding of substantial variation in the quality and depth of vitamin D knowledge is in line with findings from studies of other patient groups and the general population, 18,[20][21][22] including our study of patients with skin cancer which used an identical study design and similar topic guide. 19 Lack of knowledge of vitamin D-rich food sources was particularly evident with many patients wrongly believing that a "healthy diet" of meat, fruit and vegetables could provide adequate vitamin D.
Furthermore, while many patients related vitamin D with bone health, awareness of the effects of vitamin D deficiency was limited to occurrence of rickets in childhood. This was also found in our previous study 19 and is likely due to the emphasis the media puts on rickets in relation to vitamin D deficiency. The lack of knowledge of complications that arise from vitamin D deficiency in adulthood may explain why few patients in our study had pre-existing concern about their vitamin D status and its impact on their health. Our data highlight the need to educate people with photosensitivity disorders on the importance of vitamin D for health, consequences of deficiency and their need for increased oral intake of vitamin D, including supplements. Enhancing awareness supports the SACN recommendation to have a dietary vitamin D intake of 10 μg daily, 6 whether this is from food or supplements, and could encourage people with photosensitivity disorders to follow this.
We found the most common source of information on vitamin D