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. 2020 Jul 20;2020(7):CD013684. doi: 10.1002/14651858.CD013684

Kötter 2016.

Study characteristics
Methods Study design: RCT
Study grouping: parallel group
Unit of randomisation: individuals
Power (power & sample size calculation, level of power achieved): With 39 students per group, the trial would have been powered to detect medium‐to‐large effect sizes (d = 0.65) for the difference in Perceived Medical School Stress German version (PMSS‐D) (SD 7.8), using a 2‐tailed test, α = 0.05 and an 80% power level. This number was determined using G*Power. In order to allow for a 10% dropout, the target sample size for the trial was 43 students per group (intervention groups 1 and 2 and control group 3)
Imputation of missing data: missing values substituted following rules provided in handbooks for instruments; incomplete data sets were excluded; missing data from responses (IG: n = 5, CG: n = 7) imputed through last‐observation‐carried forward method of imputation (conservative method chosen due to equal dropout in IG and CG); per‐protocol analysis and intention‐to‐treat analysis (with 105 participants); as per‐protocol analysis yielded very similar results, only intention‐to‐treat analysis reported
Participants Country: Germany
Setting: medical students registered for first medical examination at the University of Lübeck; training setting not specified
Age: mean = 24.2 (SD = 2.6) years
Sample size (randomised): 1) randomisation (treatment (group 1 or 2) vs control group): 129; 2) randomisation to group 1 or 2 (only participants assigned to treatment group): 67
Sex: 70 women, 35 men (of 105 participants)
Comorbidity (mean (SD) of respective measures in indicated, if available) at baseline: depression (HADS‐D; range = 0 ‐ 21) after randomisation 1 as well as after psychoeducative seminar: IG (coaching group): 3.88 (2.87), CG: 4.05 (3.72); anxiety (HADS‐D; range = 0 ‐ 21): IG (coaching group): 7.87 (3.39), 7.55 (4.30); perceived stress (PMSS‐D): IG (coaching group): 29.60 (6.57), CG: 28.74 (6.90)
Population description: medical students
Inclusion criteria: 1) registration for the first medical examination (“Physikum”) by mid‐July 2014 at University of Lübeck
Exclusion criteria: after randomisation 1 (to treatments vs control group): 1) participants who did not do a test necessary to fulfil the exam admission requirements
Attrition (withdrawals and exclusions):

  • withdrawals: 1 (IG1; seminar + coaching) discontinued intervention

  • lost to follow‐up at t2: IG1: 2; IG2: 1; CG: 1; missing data from responses: IG: 5, CG: 7


Reasons for missing data: for losses to follow‐up: no reasons specified; for 1 withdrawal in IG1: refused to participate in 2. coaching session; for missing data from responses: not specified
Interventions Intervention 1: psycho‐educative seminar + individual coaching (after 1) 24 exclusions due to not passing test necessary to fulfil exam admission requirements and 2) randomisation: 34)

  • delivery: a) psycho‐educative seminar: face‐to‐face group setting; b) coaching: face‐to‐face; individual setting + USB stick with music

  • providers: a) psycho‐educative seminar: psychologist; b) coaching: trained psychologists and physicians (manual‐based)

  • duration of treatment period and timing: a) psycho‐educative seminar: 1 hour; coaching: b) coaching: 2 x 1‐hour sessions within interval of 2 weeks; 20 minutes daily listening to music during examination preparation phase

  • description (content, components):

    • PSYCHO‐EDUCATIVE SEMINAR: psychologist addresses issues, such as emotional reactions toward stressors, unconscious persistence of unprocessed negative emotions, and the relationship of the processing of stressful events and sleep

    • RESOURCE‐ORIENTED INDIVIDUAL COACHING: based on wingwave® (Besser Siegmund Institut, Hamburg, Germany) method; wingwave uses a finger‐strength test derived from the Bi‐Digital‐O‐Ring‐Test for the determination of unconscious stressors following a standardised protocol; in order to process identified stressors, elements of eye movement desensitisation and reprocession, and neurolinguistic programming techniques are applied; coaching not primarily designed to identify and treat deficits but to foster individual stress‐management resources (“resilience”)

    • Coaching session 1: participants receive USB stick containing hemisphere‐stimulating music and are instructed to use it; instructed to listen to 20‐minute piece of electronic music twice daily, before and during learning

  • compliance: all 34 participants received allocated intervention; 1 discontinued intervention (refused to participate in 2. coaching session)

  • integrity of delivery: coaching is manual‐based

  • economic information: to reduce potential dropout rates, participants received a book voucher worth EUR 5 per completed questionnaire

  • theoretical basis: coaching based on wingwave® (Besser Siegmund Institut, Hamburg, Germany) method


Intervention 2: psycho‐educative seminar (after 24 exclusions due to not passing test necessary to fulfil exam admission requirements and 2. randomisation: n = 33)

  • delivery: psycho‐educative seminar: face‐to‐face group setting + USB stick with music

  • providers: psycho‐educative seminar: psychologist

  • duration of treatment period and timing: psychoeducative seminar: 1 hour; 20 minutes daily listening to music during examination preparation phase

  • description:

    • PSYCHO‐EDUCATIVE SEMINAR: psychologist addresses issues, such as emotional reactions toward stressors, unconscious persistence of unprocessed negative emotions, and the relationship of the processing of stressful events and sleep

    • following psycho‐educative seminar, participants in this group also receive USB stick containing hemisphere‐stimulating music and instruction sheet explaining how to use it; instructed to listen to 20‐minute piece of electronic music twice daily, before and during learning

  • compliance: all 33 participants received allocated intervention; 0 discontinued intervention

  • integrity of delivery: not specified

  • economic information: to reduce potential dropout rates, participants received a book voucher worth EUR 5 per completed questionnaire

  • theoretical basis: not specified


IG1 and IG2 were combined in analysis, thus: IG (coaching group): n = 67, CG: n = 38
Control: no intervention (after 24 exclusions due to not passing test necessary to fulfil exam admission requirements: n = 38)

  • compliance: all 38 participants received allocated intervention; 0 participants discontinued intervention

  • economic information: to reduce potential dropout rates, participants received a book voucher worth EUR 5 per completed questionnaire
Outcomes Outcomes collected and reported:

  • stress ‐ PMSS‐D

  • depression ‐ HADS‐D

  • anxiety ‐ HADS‐D

  • self‐rated general health ‐ single item


Time points measured and reported: 1) during intervention, after psycho‐educative seminar in groups 1 and 2, but before examination preparation phase and coaching (t1); 2) post‐intervention (after seminar and coaching, but directly before examination; t2)
Adverse events: not specified in this report; qualitative analyses to ask about adverse events (results will be published separately)
Notes Contact with authors: no correspondence requiredStudy start/end date: recruitment in 2014; see trial registration: July – September 2014Funding source: support and funding by Lübeck Medical School, especially Jürgen WestermannDeclaration of interest: 1 author is certified wingwave® coach and acted as 1 of the coaches in the study; authors declare no additional conflicts of interestEthical approval needed/obtained for study: approved by the Ethics Committee of the University of Lübeck (File reference 14‐098)Comments by study authors: registered with the German Clinical Trials Register (DRKS00006349); study acronym: LUST_wingwave; due to unexpected shortfall in the sample size (24 students did not pass a test necessary to fulfil the examination admission requirements, Figure 1), decision to combine both intervention groups for the quantitative analysesMiscellaneous outcomes by the review authors: not relevantCorrespondence: Thomas Kötter; Institute of Social Medicine and Epidemiology, University of Lübeck, Ratzeburger Allee 160, 23562 Lübeck, Germany; Tel +49 451 500 5874; Fax +49 451 500 5455; thomas.koetter@uksh.de
Risk of bias
Bias Authors' judgement Support for judgement
Random sequence generation (selection bias) Unclear risk Quote: "After preliminary enrolment, we randomly allocated participants to the treatment (groups 1 and 2) or control group (group 3) using a computer‐generated random numbers table (randomization 1)."
Quote: "In a second step, the participants in the treatment group were randomly allocated to treatment groups 1 and 2 (randomization 2)."
Quote: "Table 1 displays baseline characteristics for all participants included. Overall, 35 male and 70 female students (M =24.2 years, SD =2.6) with an age range between 19 and 32 years participated in this study (66% of the whole class). The study participants were 0.5 years younger and the percentage of females was higher when compared to the whole class. We had a lower percentage of male participants in the coaching group and participants in this group were 0.5 years older (Table 1)."
Judgement comment: The investigators describe a random component in the sequence‐generation process (computer‐generated random numbers table) for randomisation 1 (treatment in group 1 or 2 vs control group); insufficient information about random‐sequence generation for randomisation 2 (to group 1 or 2); verified comparability between groups at assessment t1 (i.e. after randomisation 1 and psychoeducative seminar, but before coaching in group 1) for outcome variables (see Table 2; all Ps > 0.42); insufficient information about comparability of groups in sociodemographic characteristics (e.g. smaller percentage of male participants in CG, but statistical (non)significance not specified); insufficient information about baseline comparability BEFORE psycho‐educative seminar
Allocation concealment (selection bias) Unclear risk Quote: "By inviting those participants in the treatment group to participate in the psychoeducative seminar (described earlier), the students were immediately informed of their allocation to either control or treatment group. In a second step, the participants in the treatment group were randomly allocated to treatment groups 1 and 2 (randomization 2). This allocation was concealed by means of sealed, opaque envelopes until the end of the psychoeducative seminar and the t1 survey."
Judgement comment: insufficient information about allocation concealment for randomisation 1 (treatment (group 1 or 2) vs control group); for randomisation 2, participants and investigators enrolling participants could probably not foresee assignment (sealed, opaque envelopes)
Blinding of participants and personnel (performance bias)
Subjective outcomes High risk Quote: "By inviting those participants in the treatment group to participate in the psychoeducative seminar (described earlier), the students were immediately informed of their allocation to either control or treatment group. In a second step, the participants in the treatment group were randomly allocated to treatment groups 1 and 2 (randomization 2). This allocation was concealed by means of sealed, opaque envelopes until the end of the psychoeducative seminar and the t1 survey. The participants, coaches, and the involved researcher were not blinded hereafter."
Judgement comment: 1) no blinding of participants and personnel (for allocation to treatment (group 1 or 2) or control group after randomisation 1 nor for allocation to treatment group 1 or 2 after randomisation; and 2) the outcome is likely to be influenced by lack of blinding
Blinding of outcome assessment (detection bias)
Subjective outcomes High risk Quote: "Also, as group allocation was not concealed; t1 measures were completed after randomization; and the students, coaches, and investigators were not blinded, the differences between the groups at both t1 and t2 might have been influenced by a certain amount of frustration in the control group in not having received coaching."
Judgement comment: probably no blinding of outcome assessment (e.g. group allocation after randomisation 1 not concealed and study personnel/participants were not blinded) and the outcome measurement is likely to be influenced by lack of blinding; unclear blinding for t2 assessment (web surveys); but due to performance bias (no blinding of participants), the review authors judge that the participants' responses at t2 assessment to questionnaires may also be affected by the lack of blinding (i.e. knowledge and beliefs about intervention they received)
Incomplete outcome data (attrition bias)
All outcomes Low risk Quote: "We substituted missing values following the rules provided in the handbooks for the instruments, that is, through interpolation where tolerable. We then excluded incomplete data sets."
Quote: "Data were missing from the responses of five students in the intervention group and seven in the control group, respectively. The last‐observation‐carried‐forward method of imputation was chosen because this is a conservative method used in instances in which there is an equal dropout rate in the intervention and the control group."
Quote: "Intention‐to‐treat and per‐protocol analyses yielded very similar results and we therefore present only the former."
Judgement comment: reasons for missing data unlikely to be related to true outcome with relative balance in missing data between groups (lost to follow‐up: IG1: 2; IG2: 1, CG: 1; missing data from responses: IG: 5, CG: 7); no reasons for missing data specified for each group; per‐protocol analysis and intention‐to‐treat analysis after last‐observation‐carried‐forward method of imputation (see Table 2)
Selective reporting (reporting bias) High risk Quote: "The trial was approved by the Ethics Committee of the University of Lübeck (File reference 14‐098) and registered with the German Clinical Trials Register (DRKS00006349)"
Judgement comment: trial registration available (DRKS00006349) and all of the study’s prespecified (primary and secondary) outcomes have been reported in the prespecified way; but according to trial registration 3 assessments (t1 before coaching/examination preparation phase; t2 after individual coaching and directly before the examination; t3 after the examination "Physikum"), but only t1 and t2 reported