Phototherapy and Home Phototherapy for Vitiligo 3
64. What initial dose should be chosen for 308nm UVB? Is there a difference among different populations?
Currently, there is no guideline clearly specifying the exact initial dose for 308nm UVB phototherapy. Clinically used 308nm UVB also belongs to narrowband UVB (NB-UVB), so its initial dose can be the same as that of 311nm UVB. It is recommended to use 70% of the minimal erythema dose (MED) as the initial treatment dose. However, the irradiation area of 308nm phototherapy devices is generally small, so some doctors may adopt a relatively higher initial dose, such as 300mJ/cm². For pediatric patients, the recommended dose is 70% MED.
65. Is the initial irradiation dose the same for skin lesions in different body parts?
The same initial irradiation dose of 200mJ/cm² can be used for different body parts, or 70% of the MED of the specific body part can be used as the initial irradiation dose. Since the photosensitivity of areas such as the eyelids and mucous membranes is 4–6 times higher than that of acral areas, the irradiation dose for the eyelids and mucous membranes should be lower than that for acral areas after a period of treatment.
66. Is the irradiation dose for children the same as that for adults?
The irradiation dose for children is basically the same as that for adults. The general initial dose is 200mJ/cm², and 70% of the MED of the specific body part can also be used as the initial irradiation dose.
67. Is a higher irradiation dose better for phototherapy?
A higher irradiation dose is not better for phototherapy. The irradiation dose should be increased gradually during phototherapy. Once the specified maximum irradiation dose for the target area is reached, no further increase is allowed, and treatment should continue with the specified maximum irradiation dose. If the irradiation dose is continuously increased to an excessive level, it may cause acute photodamage, and long-term high-dose irradiation can lead to issues such as skin photoaging.
68. Will adhering to daily phototherapy result in better efficacy?
No. The efficacy of phototherapy depends on the total irradiation dose. Studies have shown that the efficacy of phototherapy administered 5 times a week is the same as that of 3 times a week. However, excessively frequent phototherapy will increase the cumulative dose and raise the risk of adverse reactions such as photoaging (Figure 3-7). (Figure 3-7: Currently, clinical practice generally recommends intermittent daily phototherapy. The left panel shows "daily phototherapy is not advisable," and the right panel shows "intermittent daily phototherapy is more scientific.")
69. How many times a week is appropriate for 311nm UVB treatment?
It is recommended to undergo treatment 2–3 times a week. The effect of repigmentation depends on the total number of treatments. Comparatively, a frequency of 3 times a week will lead to earlier repigmentation, which enhances patients' confidence. The Vitiligo Working Group recommends 3 times a week as the optimal treatment frequency. Therefore, for home phototherapy, treatment should be conducted 3 times a week; for hospital-based phototherapy, treatment should be conducted at least 2 times a week.
70. How many times a week is appropriate for 308nm UVB treatment?
For 308nm UVB treatment in hospitals, the frequency is generally 1–2 times a week due to the relatively high dose used. For home-based 308nm UVB phototherapy, it is recommended to adopt a frequency of 2–3 times a week.
71. Is it necessary to increase the irradiation dose each time compared to the previous one? Why?
It is not always necessary to increase the dose; a dose reduction may also be required. The irradiation dose for the current phototherapy session should be determined based on the skin reaction after the previous session. Mild erythema after phototherapy that subsides within 24 hours indicates the optimal dose, which achieves the best efficacy while minimizing adverse reactions. A dose that is too low will not induce erythema and thus fail to achieve therapeutic effects; an excessively high dose may cause adverse reactions such as pain and blisters. Therefore, the dose should be adjusted based on the skin reaction after the previous irradiation: (1) If no erythema occurs or erythema lasts for less than 24 hours after 4 consecutive sessions with the same dose, the treatment dose should be increased by 10%–20% until the single irradiation dose reaches the recommended maximum dose for the target area (for skin types III and IV). (2) If erythema lasts for 24–72 hours, the original irradiation dose should be maintained for subsequent treatment. (3) If erythema lasts for more than 72 hours or blisters occur, treatment should be postponed until the symptoms subside, and the dose for the next session should be reduced by 10%–50%. If a plateau phase is reached (i.e., no repigmentation occurs after 20–30 consecutive irradiation sessions), treatment should be stopped, and a 3–6-month rest period should be observed. Then, treatment can be restarted with the MED dose (different from the 70% MED used for initial treatment). Treatment should be stopped if no efficacy is observed after 3 months. Phototherapy can be continued as long as continuous repigmentation is observed.
72. Is there a maximum limit for a single irradiation dose? What are the single irradiation doses for 311nm UVB and 308nm UVB?
There is a maximum limit for a single irradiation dose. Clinically, both 311nm and 308nm UVB belong to NB-UVB, so the maximum NB-UVB irradiation dose specified in guidelines can be uniformly applied. According to skin typing, most people in China have skin types III and IV. For vitiligo patients with these skin types, the maximum single irradiation dose is 1500mJ/cm² for the face and 3000mJ/cm² for the limbs and trunk.
73. If no erythema appears on the local skin after several consecutive phototherapy sessions, how should the dose be adjusted for the next session?
According to the principles of dose adjustment, for vitiligo lesions, if no erythema occurs or erythema lasts for less than 24 hours after 4 consecutive sessions with the same dose, the dose for the next session should be increased by 10%–20%. This adjustment should be repeated until the single irradiation dose reaches the recommended maximum dose for the target area.
74. If erythema appears on the day after phototherapy but lasts for less than 24 hours, how should the dose be adjusted for the next session?
In this case, the dose for the next session can be increased by 10%–20%.
75. If erythema appears on the day after phototherapy and lasts for 24–72 hours, how should the dose be adjusted for the next session?
If erythema appears on the day after phototherapy and persists for 24–72 hours, the same irradiation dose as the current session should be maintained for the next treatment.
76. If erythema appears on the day after phototherapy and lasts for more than 72 hours, how should the dose be adjusted for the next session?
The occurrence of this situation indicates that the irradiation dose was too high. The next phototherapy session should be conducted only after the erythema has completely subsided, and the dose should be reduced by 10%–50% compared to the previous session.
77. What is the reason for no repigmentation after a long period of single-session phototherapy?
This may indicate that the phototherapy has reached the plateau phase. The plateau phase refers to a stage where no further repigmentation of white patches occurs after 20–30 consecutive phototherapy sessions. The plateau phase occurs because the photosensitivity of the target skin area decreases with the increase in the number of irradiation sessions and the accumulation of treatment time. At this point, phototherapy should be suspended for 3–6 months, after which treatment can be restarted.
78. What is the reason for normal skin around the treated area darkening after phototherapy while the white patches show no change?
The absence of darkening in white patches while pigmentation appears in normal skin is a common phenomenon in the initial stage of vitiligo phototherapy, and it may be a manifestation of the marginal repigmentation pattern. There are three patterns of repigmentation for vitiligo lesions: (1) Perifollicular repigmentation pattern (punctate type): Punctate pigment islands form centered on hair follicles and gradually expand outward, indicating that the melanocytes for repigmentation originate from hair follicles. (2) Marginal type: Repigmentation starts from the edge of the lesion and gradually contracts toward the center. Initially, it manifests as darkening around the lesion, which gradually contracts toward the lesion, leading to a gradual reduction in the area of the white patch. (3) Uniform type: The color of the lesion area darkens uniformly after treatment until complete repigmentation is achieved.
79. What is the reason for the improvement of lesions in the irradiated area after phototherapy while new white patches appear in other areas?
The appearance of new white patches indicates that vitiligo is in the progressive stage. Studies have confirmed that vitiligo is an autoimmune disease, and it is often associated with other autoimmune diseases, such as thyroid diseases. Therefore, during the progressive stage, if no other drugs are used to control the immune damage to melanocytes, even if melanocytes in the treated area are recovering, melanocytes in other skin areas may be damaged simultaneously. This may lead to the improvement of some vitiligo lesions while new lesions occur.
80. If the treated area improves after phototherapy but new white patches appear in other areas, how should phototherapy be continued?
The improvement of the irradiated area indicates that phototherapy is effective. However, the simultaneous appearance of new white patches indicates that the disease is still in the progressive stage. At this point, phototherapy alone is difficult to control the disease, so patients should seek medical attention promptly. They may need to be treated with oral or injectable glucocorticoids to control the disease as soon as possible. In addition, the initial irradiation dose for new white patches should be 100mJ/cm², and subsequent dose increases should be carried out in accordance with the dose adjustment principles.
81. If the repigmentation speed of white patches varies in different areas after phototherapy, how should the treatment plan be adjusted?
Due to differences in skin thickness and photosensitivity among different body parts, the repigmentation speed of vitiligo varies in different areas, and the speed of dose increase for irradiation also differs. At this point, the irradiation dose should be adjusted separately based on the response of each area to phototherapy: for areas with poor efficacy and slow repigmentation, the speed of dose increase can be slightly accelerated. Once the maximum irradiation dose for the target area is reached, no further increase is allowed, and treatment should continue with the maximum single irradiation dose. As a result, the single irradiation time may vary among different areas during phototherapy. Therefore, patients should keep detailed treatment records, including the treated areas and the irradiation doses used, to ensure scientific and regular treatment.
82. What does the treatment plateau phase mean?
For vitiligo patients undergoing NB-UVB phototherapy, after a certain number of treatments (usually 20–30 consecutive sessions), no further increase in repigmentation of white patches occurs even if treatment is continued. This indicates that the treatment has entered the plateau phase. If the plateau phase is reached, it is recommended to suspend phototherapy for 3–6 months, which helps the skin recover its photosensitivity. Meanwhile, the treatment plan can be changed under the guidance of a doctor.
83. Is it necessary to adjust the treatment plan after reaching the plateau phase?
Yes, adjustments are necessary. If phototherapy enters the plateau phase, phototherapy should be suspended, and the treatment plan should be changed under the guidance of a doctor. After 3–6 months, phototherapy can be restarted with the MED as the initial dose.
84. What should be done if the initial efficacy of phototherapy is obvious but there has been no change recently?
This situation may be due to the skin becoming insensitive to phototherapy. In this case, combined therapies such as drug treatment or fractional laser therapy can be used. It may also indicate that the treatment has entered the plateau phase. In this case, phototherapy can be suspended for 3–6 months and then restarted with the MED as the initial dose.
85. What is the reason for no efficacy after nearly 2 years of phototherapy?
If no efficacy is observed after nearly 2 years of phototherapy, it indicates that phototherapy is ineffective for the patient. At this point, other treatment methods should be adopted, such as topical medications, oral medications, laser therapy, or surgical treatment.
86. Is there an upper limit for the total number of phototherapy sessions?
Currently, there is no regulation on the upper limit of the total number of phototherapy sessions, nor are there regulations on the number of consecutive sessions or the duration of NB-UVB use. Treatment should be considered for termination when the condition improves or no further improvement is observed. Some patients may experience a recurrence after being cured by phototherapy. Even if they have undergone many phototherapy sessions before, they can still choose to use phototherapy again after recurrence, without being restricted by the number of previous sessions.
87. When can phototherapy be stopped?
Phototherapy can be stopped in two situations: one is when phototherapy is ineffective, and the other is when the lesions have achieved complete repigmentation. Method for determining ineffective phototherapy: According to the latest international phototherapy guidelines, at least 18–36 phototherapy sessions are required to evaluate the treatment response. Clinical experience suggests that most patients need to complete at least 48 NB-UVB sessions before evaluating whether to terminate treatment due to ineffectiveness. For some patients with a slow response to phototherapy, the evaluation period can be extended to 72 sessions before deciding whether to terminate treatment due to ineffectiveness. Phototherapy can be stopped after complete repigmentation of lesions. Some scholars also recommend maintenance therapy after complete repigmentation, i.e., reducing the phototherapy dose and frequency to prevent recurrence.
88. What is the course of home phototherapy for vitiligo patients?
The course of home phototherapy is the same as that of hospital-based phototherapy. The standard treatment is 2–3 sessions per week, with an interval of at least 24 hours between each session, and the treatment cycle is at least 3 months. Depending on the repigmentation situation, phototherapy can be continued for a longer period. In short, phototherapy can be continued as long as continuous repigmentation is observed.
89. Is it necessary to continue phototherapy after the white patches fade?
There are different opinions at home and abroad on whether to continue phototherapy after complete repigmentation of lesions. The 2018 edition of the Chinese Clinical Consensus on Vitiligo Diagnosis and Treatment does not recommend maintenance phototherapy for vitiligo patients. However, the NB-UVB Phototherapy Consensus of the Vitiligo Working Group suggests that maintenance phototherapy can be performed after repigmentation of white patches to reduce the risk of recurrence. The consensus points out that once the optimal repigmentation level is achieved, the NB-UVB dose can be gradually reduced according to the following plan: within the first month after repigmentation, phototherapy is performed 2 times a week; the frequency is reduced to once a week in the second month; and reduced to once every other week in the third and fourth months. If no recurrence occurs, phototherapy can be stopped.
90. Will failure to adhere to the specified treatment frequency affect the efficacy of phototherapy?
Yes. Adhering to the treatment plan can significantly improve clinical efficacy, i.e., undergoing phototherapy 2 or 3 times a week. Data show that treatment interruption (missing more than 2 phototherapy sessions within 4 weeks) may affect the efficacy.
91. How should the dose be adjusted after treatment interruption?
Patients should adhere to the treatment plan for phototherapy to achieve the best efficacy. If phototherapy is interrupted, the treatment plan should be readjusted considering the changes in skin photosensitivity. The dose adjustment varies according to the duration of the interruption: if the interruption lasts for 4–7 days, the original dose should be maintained; if it lasts for 8–14 days, the original dose should be reduced by 25%; if it lasts for 15–21 days, the original dose should be reduced by 50%; and if it lasts for more than 3 weeks, treatment should be restarted with the initial dose.
92. What is the difference in phototherapy plans between the progressive stage and stable stage of vitiligo?
The initial irradiation dose for the rapidly progressive stage should be lower than that for the stable stage, generally 1/3–1/2 of the dose used in the stable stage. Subsequent doses should be increased based on the patient's erythema response after phototherapy. This is because if the irradiation dose is too high during the progressive stage, it may cause skin burns and induce the Koebner phenomenon, which worsens the condition.
93. What are the advantages of combining phototherapy with other therapies for vitiligo treatment?
Combined therapy is usually adopted for vitiligo treatment. Compared with monotherapy, combining phototherapy with other therapies has the following advantages: (1) Faster and better efficacy, which can produce effects more quickly and enhance patients' confidence and compliance with treatment. (2) Combined phototherapy can reduce the cumulative dose of phototherapy and alleviate long-term adverse reactions such as photoaging. (3) Compared with the single use of drugs, combining phototherapy with drugs can reduce the dosage of drugs and their adverse reactions.
94. Which topical drugs are often combined with phototherapy?
Phototherapy for vitiligo can be combined with a variety of topical drugs, such as glucocorticoid ointments (dexamethasone, betamethasone, halometasone, fluticasone ointments, etc.), calcineurin inhibitors (tacrolimus, pimecrolimus creams), low-concentration photosensitizers (compound kaliziran tincture, psoralen tincture), and vitamin D₃ derivatives (calcipotriol, tacalcitol ointments). In certain skin inflammation management scenarios, red light therapy pimples can also serve as an adjunct to alleviate post-phototherapy localized inflammation, while red led light therapy is sometimes used to promote skin repair; blue light therapy at home can be supplemented at home for acne-like reactions, and ultraviolet light therapy remains the core approach.
95. What is the timing sequence between phototherapy and topical drugs when they are used in combination?
Drugs containing petrolatum or lanolin can increase the thickness of the outer skin layer and hinder the absorption of ultraviolet rays. It is generally recommended not to apply any drugs, cosmetics, or skincare products within 4 hours before irradiation to avoid affecting the penetration of ultraviolet rays. Some professional mineral oils can be used to promote light penetration and also play a role in moisturizing and protecting the skin. Topical drugs can be applied after phototherapy. However, some experts believe that ointments that may cause skin irritation, such as calcipotriol ointment and retinoic acid cream, should not be applied immediately after phototherapy, and an interval of 2 hours is recommended before application. Immediately after ultraviolet light therapy, using red led light therapy can further soothe the skin.
96. Can home phototherapy be combined with topical photosensitizers such as compound kaliziran tincture?
The combination of the two is not recommended. The instruction manual of compound kaliziran tincture suggests that sunlight exposure should be performed after its application to achieve therapeutic effects. However, the spectrum of home ultraviolet phototherapy is mostly NB-UVB, which is different from the spectrum of sunlight. If a doctor has prescribed compound kaliziran tincture and the patient is also undergoing home ultraviolet phototherapy, it is recommended to use the two alternately, i.e., not using compound kaliziran tincture on the day of phototherapy. When necessary, blue light therapy at home can be combined at home to manage photosensitivity reactions, or red light therapy pimples can be used to alleviate localized discomfort; ultraviolet light therapy still needs to be strictly followed in terms of dosage.
