David J. Abels, M.D., and Jonathan Kattan-Byron, M.D. Beer-Sheva, Israel

A naturally filtered ultraviolet spectrum of sunlight along with other natural factors are utilized in the management of psoriasis at the Dead Sea area in Israel. In 110 patients with psoriasis, 85.5% achieved complete clearing or excellent improvement. These results compare favorably with other therapeutic regimens used today in the treatment of psoriasis. Since systemic medications are avoided, the potential risks may be considerably lessened. Therefore, this therapeutic modality may be considered in the management spectrum of psoriasis. (J AM ACAD DERMATOL 12:639- 643, 1985.)

Since the advent of PUVA1, the combination of psoralen (P) and long-wave ultraviolet radiation (UVA), the management of psoriasis has taken on a new dimension. Numerous scientific articles have been written discussing this form of treatment and elucidating the principles involved that are presently being defined. Concurrent with this knowledge, much more is now understood about photobiologic mechanisms and the UV spectrum.2.3 Along with this basic knowledge, phototherapy has progressed today into a well-accepted treatment in most major medical centers. Selective ultraviolet phototherapy (SUP), first described in the European literature, is currently gaining popularity and many phototherapy units are now utilizing this principle.4

Climatotherapy, defined as a treatment combining the natural elements of a specific geographic location, has been used at the Dead Sea in Israel for over twenty years.5.6 Because of its unique position, the treatment at the Dead Sea mainly consists of the patients being exposed to a UV spectrum of long-wave ultraviolet light found naturally in high intensity7 only in that area of the world and, in addition, a sea rich in natural minerals and salts. This study of 110 patients with psoriasis confirms the value of this treatment with the results comparable to other established treatments used today in the management of psoriasis.

METHODS
During the period of time from the end of March 1983 to June 1983, we investigated 110 patients enrolled in a Dermatology Clinic at the Dead Sea in Israel sponsored by the Israeli government. Since the study was primarily designed for the treatment of psoriasis, patients with other skin diagnoses were eliminated from the study.

Ten patients with psoriasis were also excluded: one because excessive alcoholic intake interfered with treatment compliance; a second patient because he remained under treatment for only 1 week, which is considered insufficient time; a third patient was not included because her primary diagnosis was in doubt; the fourth, because he failed to follow the treatment regimen; the fifth, because her primary diagnosis was psoriatic arthritis and she had no skin involvement; and the last five patients, because they left the treatment without a final examination. All the other patients were randomly included and no selective basis was utilized.

As mentioned, all patients included in this study had a diagnosis of psoriasis. The main type was plaque or patchy involvement with six patients having psoriasis guttata. The psoriatic involvement was visually estimated at the start and conclusion of treatment and the patients were examined always by the same two physicians, providing relative consistency to the findings. The treatment consisted primarily of sun exposure beginning with 10 to 20 minutes, depending on the skin type, in the morning and the same in the afternoon, with an increase in increments of 10 minutes each day until a maximum of approximately 6 hours per day was reached. Bathing in the Dead Sea was highly variable but routinely it began with 5 minutes in the morning and the same in the afternoon, increasing every 3 days another 5 minutes until 30 minutes in the morning and 30 minutes in the afternoon was obtained. All patients were examined on a daily basis and treatment was adjusted as required.

Topical medications included petrolatum, body and bath oils, and various concentrations of sulfur-salicylic acid ointments principally used for keratolytic purposes. In selected patients, a tar ointment was added toward the end of treatment, mainly for its UV-enhancing effect. Scalp treatments were administered by a nurse on a daily basis as needed and consisted mainly of localized applications of sulfur-salicylic acid ointments. Shampooing of the scalp was with a 5% cetrimide shampoo with or without tar added. At no time was any other topical or systemic medication used in the treatment. No topical or systemic corticosteroids were utilized.

The patients underwent treatment from a minimum of 14 days to a maximum of 42 days, with the average patient stay at the Dead Sea being 26 days.

RESULTS
Of the 110 patients included in this study, 56 were male and fifty-four female. The youngest was 10 and the oldest 76, with the average 43 years of age.
The range of psoriatic involvement at the beginning of treatment was from 1% to 90% (Table I) with the average involvement at the start of 29%. The percentage improvement was classified into groups (Table II) and defined as minimal improvement, 5% to 20%, no patients; definite improvement, 20% to 50%, one patient; considerable improvement, 50% to 80%, fifteen patients; excellent improvement, 80 to 95%, 32 patients; complete clearing, 95% to 100%, sixty-two patients. The percentage improvement was estimated relative to the original extent of disease.

Forty-three patients had 30% or greater coverage with psoriasis (Table I). In analyzing the patients in this group, 81.4% showed complete clearing or excellent improvement. In the group with 20% to 29% involvement, 93.3% had complete clearing or excellent improvement. Those with 10% to 19% involvement had 75% complete clearing or excellent improvement, and all thirteen patients with 0% to 9% involvement showed complete clearing or excellent improvement.

Included in other findings, thirty-one patients (28%) gave a history or had evidence of psoriatic arthropathy. Virtually all patients expressed some degree of improvement in their arthritic symptoms at the time of discharge. Fifty-two patients (47%) revealed nail changes characteristics of psoriasis.

No significant complications were encountered. Occasionally a patient experienced transient pustules primarily on the legs that cleared with topical antibiotics. Unrelated ear or skin infections occurred infrequently and responded to appropriate therapy. In a few patients, a pruritic sunburn-like erythema or a sun sensitivity appeared early in treatment but always resolved after several days avoidance of sun exposure to the affected areas. Only very rarely did blistering accompany the sunburn-like erythema, and it responded to local treatment.

DISCUSSION
The Dead Sea area, situated 390 meters below sea level, is the lowest place on earth and consequently has certain characteristic atmospheric and climatic features present at no other location in the world. First, the Dead Sea itself has the highest concentration of salts found in any natural body of water. These salts are present in a total concentration of 33% as compared, for example, to the Great Salt Lake in Utah at 20% to 27% or the ocean, at 3%. Magnesium chloride is the salt with the highest concentration at 50%, with sodium chloride, 25%, calcium chloride, 12%, and potassium chloride, 4%.k In the sea, bromides are also found in significant concentration.

*Compared to original involvement of psoriasis

These elemental properties of the sea are combined with unique photobiologic characteristics that are also present only in this area. The sunburn spectrum of ultraviolet light is very weak at the Dead Sea9 because of a continuous haze that develops over the water. This haze or mist occurs from an extraordinarily high water evaporation estimated at two billion cubic meters per year. Subsequently, the majority of UVB sunburning rays are filtered out, thus allowing a greater exposure to the longer wavelength UVB and penetrating natural UVA rays.

These two major factors, the sea and the sun, have served as a basis for the management of many different medical illnesses at the Dead Sea, particularly dermatologic disorders. Psoriasis has been the main skin disease treated, although atopic dermatitis, neurodermatitis, vitiligo, acne, and ichthyosis have responded to this treatment. From our experience and also that of others,10 the principal climatic factor at the Dead Sea accounting for the benefit seen, particularly in psoriasis, most likely is the naturally filtered spectrum of UVA and the longer wavelength UVA. Because of this, we are most probably dealing with a form of natural selective ultraviolet phototherapy (NSUP).

PUVA, the combination of psoralen and long-wave ultraviolet radiation (UVA), is considered today as one of the major therapeutic modalities in the management of psoriasis. Since it demonstrates a high clearance rate, nearly 90%,11 it has to be considered as a treatment to which other therapeutic regimens are compared.12.13 The results in our study of 110 patients with psoriasis treated with NSUP showed that by classifying the patients according to their percentage improvement (Table II), 56.4% had complete clearing and 29.1%, excellent improvement. Grouped together, 85.5% had complete clearing or excellent improvement of their psoriasis.

This overall figure combining complete clearing and excellent improvement together would support the treatment value with NSUP and its overall efficacy would compare favorably with PUVA. All our patients responded to treatment with just one obtaining less than considerable improvement (Table II). In another study done at the Dead Sea10 77% had complete clearing or marked improvement, which is near our finding of 85.5% complete clearing or excellent improvement. To draw any further comparisons with this study is difficult because of the lack of quantification of their groups, but their findings generally correlate with our results.

It should be noted that in addition to NSUP, the treatment schedule in this study included topical medications mainly used for lubrication and keratolytic purposes. A tar ointment was added in selected patients toward the termination of treatment primarily for its UV-potentiating effect. Future data may show that a combination therapy of NSUP with an active antipsoriatic medication may significantly enhance the treatment results.

The average stay at the Dead Sea for our patients was 26 days. Even though the minimum stay was only 14 days, the eleven patients who stayed for this period of time had an average clearing of 87.5%. Many patients did not show significant improvement until the third or fourth week; therefore, we usually suggest that patients undergo treatment for a minimum of 3 weeks and preferably for a period of 4 weeks. Since some patients did experience substantial improvement after 14 days, it is likely that future work will demonstrate that on an individual basis, the period of time to achieve maximum benefit will vary between 14 and 28 days.

Psychotherapeutic influences certainly play a role in the patients?overall improvement at the Dead Sea. Grouped together for several weeks in a relaxed, pleasant atmosphere allows those affected with this chronic skin disorder to share and discuss similar frustrations and apprehensions. Many realize for the first time that they are not alone in their suffering, and visualizing their own improvement along with that of others serves as an important psychologic stimulus to their general progress.

Three additional areas requiring objective confirmation and further study are the response seen in psoriatic arthritis, possible adverse side effects, and the recurrence or relapse rate. An added advantage of NSUP was its benefits with psoriatic arthropathy. Twenty-eight percent of our patients had arthritic symptoms and all benefited from the treatment. Detailed investigation should now be undertaken to demonstrate conclusively the benefits of this treatment in psoriatic arthritis and precisely what part the sea and its minerals may also play in the therapeutic result.

Other important factors needing evaluation are particularly the long-term side effects.14 Since NSUP eliminates entirely the taking of systemic medications, such as psoralens, we are not as concerned, for instance, about the potential ophthalmologic hazards15 and the patients do not have to wear protective glasses during or after therapy.

The carcinogenic,16.17 mutagenic,18 and immunologic19 complications of the other treatments for psoriasis are now just beginning to be recognized. No investigations of these parameters have as yet been carried out at the Dead Sea, but currently we are unaware of any skin cancer appearing in any of our patients who were treated at the Dead Sea prior to this study. This certainly requires further confirmation with large numbers of patients. In the future, we also hope to study the problem of premature aging of the skin, which may possibly be a potential complication.20

The recurrence or relapse rate of the psoriasis is another important issue that also must be considered. Once more, we have no conclusive data at this time, but after interviewing several hundreds of patients who have been at the Dead Sea before, NSUP will frequently give a longer remission than other modalities without specific maintenance therapy being administered between clearance courses.10 Patients commonly mention a 3- to 6-month period of time before noticing the beginning of a relapse and state that the psoriasis frequently does not appear as severely. Further study and documentation should be forthcoming.

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From the Division of Dermatology, Soroka University Hospital and Faculty of Health Sciences, Ben Gurion University of the Negev.
Accepted for publication Nov. 15, 1984
Reprint requests to: Dr. David J. Abels, 5 Nitza Blvd., Apartment 26, Netanya, Israel 42269