Currently, few studies on the use of home phototherapy in vitiligo exist. Much of our knowledge is extrapolated from the psoriasis literature.38 Although future research is needed, we can draw some preliminary conclusions regarding the safety and efficacy of home phototherapy in vitiligo.

To be considered for home phototherapy, patients must be good candidates for in‐office phototherapy. Patients need to be motivated, able to comply with instructions, and return to clinic periodically for reevaluation. Absolute contraindications include a history of xeroderma pigmentosum or systemic lupus erythematosus. Relative contraindications are photodermatoses, immunosuppression, photodamaged skin, personal or family history of melanoma or multiple non‐melanoma skin cancers, and claustrophobia. Use of photosensitizing medications is usually not a contraindication as most of these act in the UVA range. NB‐UVB can also be used safely in children, pregnant females, and those with hepatic or renal disease. 39 Pregnant patients undergoing home phototherapy should be followed closely and extra caution should be used. Patients should complete a course of NB‐UVB phototherapy to ensure treatment responsiveness, reliability following detailed instructions, and ability to follow‐up in clinic. The consent performed prior to in‐office phototherapy can be carried over for home phototherapy. However, institutional guidelines should be followed regarding this process. Administration of home phototherapy is similar to in‐office phototherapy, with dose adjustments based on lesional erythema after treatment. Creating patient handouts with dose adjustments and instructions on how to handle missed doses is invaluable in facilitating patient understanding, ensuring compliance, and reducing adverse events (Figure 1 ).

3.2 Efficacy and safety

One of the most well‐known trials on home phototherapy is the PLUTO study,40 the first multicenter, single‐blinded, randomized, controlled trial comparing in‐office vs. home NB‐UVB phototherapy for the treatment of psoriasis. Patients in the home phototherapy arm were given a phototherapy schedule and an educational training session with a nurse. Subsequent dosing was adjusted by nurses, and the mean duration of phototherapy was 11 weeks compared to 14 weeks for in‐office phototherapy. At study completion, 70% of patients in the home phototherapy arm reached Psoriasis Area and Severity Index 50 compared to 73% in the in‐office phototherapy arm, showing that home and in‐office NB‐UVB phototherapy were equally effective. There was no difference in the number of side effects. The total dose of NB‐UVB administered, the measure of long‐term safety, was slightly higher in the home phototherapy group, but not statistically significant. Based on a survey completed by participants, none of the subjects felt that home phototherapy was unsafe.40 Cost was similar for both groups, with costs for the home phototherapy group including unit delivery, pick up, and home care. However, costs associated with time away from work were not considered. Once this variable was factored in, there was a significant cost advantage to home phototherapy.41 Patient satisfaction was greater in the home phototherapy group, with equal Dermatology Life Quality Index scores and decreased burden of treatment.40

Fewer studies have been performed on home phototherapy and vitiligo, but these have yielded similar results. A survey study from the Netherlands compared biweekly in‐office vs. home phototherapy in 104 patients (57 home phototherapy and 32 in‐office phototherapy). Results showed that home phototherapy patients received a greater number of treatments per week, with no significant difference in the cumulative dose. No significant difference was noted in the degree of pigmentation or adverse events between both groups. However, time investment was much lower in the home phototherapy group.42 Another study compared home phototherapy with a handheld NB‐UVB device 3 times per week to biweekly in‐office excimer laser in subjects with localized vitiligo. Here, home phototherapy was more effective, although this difference was not statistically significant. There was, however, increased compliance with home phototherapy, with three subjects in the excimer treatment arm withdrawing from the study due to time constraints. Regarding safety, only 1 case of UVB‐induced burn was noted in the home phototherapy group.43 A study by Shan et al. examined the use of a home NB‐UVB handheld device thrice weekly in 93 subjects with localized disease over 1 year. Repigmentation was observed 1 month after initiation of treatment and some subjects had complete repigmentation by 3 months. Dryness, pruritus, and a burning sensation were the most common side effects, but they did not lead to subject withdrawal.44

Currently, no large, multicenter, randomized controlled trials comparing in‐office vs. home phototherapy in vitiligo exist. The Hi‐Light trial was a feasibility trial for a larger multicenter effort, which randomized 29 patients with non‐segmental vitiligo to either the treatment group with 1 of 2 handheld NB‐UVB home phototherapy devices or the placebo group, using sham irradiation.45 Treatment lasted 4 months, with 3‐4 sessions per week. At completion, 84% of subjects were compliant with their treatment regimen. Greater patient satisfaction was achieved with the treatment group, and the majority of subjects said they would recommend the handheld device, as it was easy to use, portable, compact, and convenient. As this was a feasibility trial, the duration was not long enough to assess repigmentation. However, this trial provided recommendations for future trials assessing home phototherapy in vitiligo, including recruitment through primary care, skin mapping of lesions to evaluate repigmentation, defining outcomes, minimal erythema dose testing prior to initiating phototherapy, training materials on how to operate home devices, and the inclusion of active treatments in all groups.45

One of the main barriers to prescription of home phototherapy is concern over safety. Adverse effects of home phototherapy are similar to in‐office phototherapy such as burning, erythema, xerosis, and pruritus; these are often treated using emollients or topical corticosteroids. Köebnerization may occur due to phototoxic reactions. With long‐term use, photodamage and photoaging may occur.39 Data regarding the risk of cutaneous malignancy with NB‐UVB phototherapy in patients with vitiligo is mixed.46, 47

Patients at highest risk of side effects with home phototherapy are those who independently purchase units and self‐administer phototherapy without physician oversight. However, most companies require a prescription to be written by a physician. Many devices are equipped with safety features to prevent adverse events. These include controlled prescription timers, which allow for administration of a fixed a number of treatments after which a new code from the patient's physician is required, key‐locked on/off switches, and timers limiting the length of treatment. Dosimeters to enable accurate dosing, safety shields, and failsafe switches also exist.5 Physicians can track patient adherence by using an electronic data logger.48 Support staff play a crucial role in keeping risks of home phototherapy to a minimum by providing patient education. This includes shielding special sites, wearing clothing with the same cut at each session, how to recognize adverse effects and when to contact their dermatologist, how to maintain a proper treatment distance and the importance of regular follow‐up. As demonstrated by multiple studies,40, 42-45 when patients are educated regarding home phototherapy, the risks of adverse reactions are quite low and no greater than in‐office phototherapy.

A perceived lack of efficacy is another barrier to home phototherapy. Fifty‐five percent of 367 surveyed dermatologists believed that in‐office phototherapy was superior to home phototherapy, while 33% felt that greater risks were associated with home phototherapy.49 However, previous studies show that home phototherapy is equally effective as in‐office phototherapy, with greater adherence and decreased patient burden.40-45 Lack of insurance coverage is a major barrier for this form of therapy, as many patients cannot afford a home unit without assistance.50 Finally, many providers do not receive adequate training and are uncomfortable with prescribing home units. A survey administered at the Ninth Annual Dermatology Chief Residents' meeting showed that only 35% of residents received training on the use and prescription of home phototherapy, while 73% had never prescribed home phototherapy during their training.51 Another survey of dermatology residents showed that only 25% had didactics on home phototherapy and that no first‐year residents and 17% of third‐year residents were comfortable prescribing home phototherapy.52 These educational gaps in residency become treatment gaps in practice, leading to the underutilization of home phototherapy. It is imperative that residency programs rectify these knowledge gaps and provide training on the use of home phototherapy.