Prevention of seasonal affective disorder in daily clinical practice: results of a survey in German-speaking countries

We used the inventory “Deutsches Krankenhaus Adressbuch, 2015” [29] that contains all psychiatric institutions in German speaking countries as our sampling frame. We removed 58 institutions, after validation via an internet-search, because they had been closed, merged with other psychiatric institutions, or exclusively provided child and adolescent psychiatric care. Thus, the basic survey population comprised 533 psychiatric hospitals and departments in Austria, Germany, and Switzerland.

We developed a questionnaire in the German language according to established standards [30] and partly based on a questionnaire used in a former study on the use of light therapy [31]. We pre-tested the questionnaire with four psychiatrists working at the Medical University of Vienna and checked face-validity within our research team. The questionnaire was structured into a general part on acute treatment of SAD and a specific part on preventive treatment of SAD. The first part included one question on the number of patients treated for SAD in the institution and one assessing what interventions were used to treat acute depressive episodes in SAD patients. We asked about the use of light therapy, antidepressants, agomelatine, melatonin, methylphenidate, psychotherapy, lifestyle changes, diet changes, and alternative approaches. We named examples of lifestyle changes (e.g. sports, brighter homes), diet changes (e.g. vitamin D, no caffeine intake), and alternative approaches (e.g. meditation, yoga, acupuncture) to give an idea of what type of interventions were included in this category.

In the second part we asked if hospitals recommend interventions to prevent the onset of a new depressive episode in the next fall/winter in patients with a history of SAD and what timing they prefer for preventive treatment. We explicitly asked if light therapy, antidepressants, agomelatine, melatonin, methylphenidate, psychotherapy, lifestyle changes, diet changes, and alternative approaches were used as preventive treatment, and if so in how many patients, and for how long. We also asked participants to name the specific type of intervention used; e.g. the name of the antidepressants used for preventive treatment of SAD. Head of participating departments and hospitals were asked to use the years 2014/2015 as reference periods and to reflect the policies in their hospitals rather than their individual opinion in their answers.

We conducted the survey between December 2015 and April 2016. First, we sent a postal questionnaire accompanied by a cover letter and a stamped response-envelope to the heads of all psychiatric departments and hospitals from our survey population. In order to reach out to non-responders we set up a web-based survey based on the questionnaire with the software SurveyMonkey [32] in February 2016. We sent a survey-invitation to all non-responders as well as two reminder e-mails, one in March 2016, and one in April 2016, and called them once per phone.

We analysed responses mainly using descriptive statistics. Main outcomes of interest were 1) the proportion of departments and hospitals recommending preventive treatment to SAD patients, 2) the timing of preventive treatment, 3) the frequency of different interventions recommended for preventive treatment. In addition, we wanted to know the proportion of patients receiving, as well as the timing and specification of, each preventive treatment (e.g. type of antidepressant).

Switzerland, Austria, and Germany have only a small latitude cline (47°-54°), but differences in sunshine hours during winter, e.g. in February more than 100 sunshine hours in Austria and in the south of Germany compared to less than 50 h in the north of Germany [33, 34]. We assumed that this might correlate with greater demand for preventive treatment in northern regions. In our analysis Austria, Switzerland, Bavaria, and Baden-Württemberg comprised the southern region, and all other states of Germany were defined as the northern part. We also hypothesised that different health care systems and reimbursement procedures might lead to different patterns of recommendations between countries as well as the type of hospital. To explore differences in preventive treatments recommended between northern and southern regions, countries, and type of hospital, we a priori defined these subgroups. We tested for differences between these subgroups by using Fisher’s Exact Test, with a level of significance of p ≤ 0.05 for all tests, without correction for multiple-comparisons. All calculations were completed in IBM SPSS Statistics Version 24, Armonk, NY [35].

In total, 100 hospitals participated in the survey. Of these, 18 were from Austria, 71 from Germany, and 11 from Switzerland. This is reflective of a 19% (100/533) response-rate. These questionnaires summed up experience in 3.119 SAD patients over a two-year period (2014/2015). For further details on participating hospitals see Table 1.

The majority (84%) of the 96 psychiatric hospitals and departments that answered this question recommend the use of preventive interventions in order to reduce the risk of the onset of a new depressive episode in the upcoming fall/winter season in patients with a history of SAD. There is no consensus, however, on the optimal timing for preventive treatment in general: 38% (n = 81) recommend continuing acute treatment of SAD throughout the summer, 31% (n = 81) recommend to their patients to start with the preventive intervention as long as they are in remission and before depressive symptoms start (i.e. at end of summer), and 14% (n = 81) tell their patients to start with preventive treatment as soon as they feel mild depressive symptoms. The remaining institutions (17%, n = 81) use all three approaches, depending on the type of preventive treatment.

The most common types of recommended preventive interventions are lifestyle changes and antidepressants (Fig. 1).

Eighty-five percent of hospitals and departments (69/81) consider lifestyle changes a viable preventive treatment option. Those who recommend lifestyle adjustment, suggest it on average to 83% of their patients with a history of SAD. More than half of institutions recommend a permanent lifestyle change. Suggested lifestyle changes comprise exercise on a regular basis, exercise outdoors, spending time outdoors in the sunlight, striving towards a regular sleep-wake cycle, partaking in enjoyable activities (e.g. hobbies, meeting friends), spending their winter vacations in sunny regions, and trying to redecorate the home to make it brighter (Table 2).

Most departments and hospitals also consider antidepressants an acceptable preventive treatment (68/81). On average they recommend antidepressants to 70% of their SAD patients. Institutions named a variety of antidepressants that they prescribe as preventive treatment (Table 2). Bupropion XL, the only medication licensed for prevention in SAD patients, is mentioned by 7% of the 68 institutions recommending antidepressants for prevention.

Three quarter of hospitals (59/81) recommend psychotherapy as a preventive treatment. On average they suggest it to 62% of their SAD patients. Two fifths recommend continuous psychotherapy, one fifth suggests psychotherapy that lasts up to 30 weeks. Most frequently, behavioural therapy is recommended (see Table 2).

Three quarters (58/81) consider light therapy a viable option for prevention. They recommend it on average to 64% of their SAD patients. One third recommend continuation of light therapy throughout summer to their patients, while nearly half of the departments and hospitals recommend stopping during summer and starting by the end of summer before depressive symptoms occur. Most of the departments and hospitals recommend a light therapy device with 10,000 lux (Table 2).

Nearly half of the participating departments and hospitals (38/81) recommend diet changes. On average they suggest this to 71% of their SAD patients. Most advise a permanent change and advise cutting out caffeine, nicotine, and alcohol consumption, maintaining a balanced diet (e.g. Mediterranean diet), drinking enough fluids, adding vitamin D to their diet and trying to avoid heavy meals in the evening (Table 2).

Half of the hospitals recommend alternative approaches such as yoga, acupuncture, meditation or other relaxation techniques as preventive treatments to half of their SAD patients. Nearly half of the hospitals recommend agomelatine, and only a few hospitals melatonin (9/81), or methylphenidate (4/81, further details Table 2).

We found no differences in recommendations of preventive interventions between countries, regions and type of hospital (Table 3).

Comparing different types of preventive treatments between northern and southern regions, showed no statistically significant differences, except for one: 61% of hospitals and departments in northern regions recommend agomelatine, compared to 37% in southern regions (Table 4).