Prevention and Intervention of Neck Pain in Swiss Office-Workers

Change in NP-related productivity loss will be measured in percentages of the working time, using the Work Productivity and Activity Impairment Questionnaire for Specific Health Problem (WPAI German version) and converted into monetary units using individual earnings. Absenteeism is assessed by asking the participants about the number of hours missed because of NP as well as the number of hours they have actually worked. To assess presenteeism, the participants are asked to indicate on a 10-score scale how much the NP affected productivity while working, with 0 indicating no effect on productivity and 10 indicating total disability. Scoring rules of the developers of the questionnaire will then be used to obtain self-reported absenteeism and presenteeism expressed as impairment percentages. The monetary value for the lost productivity will be obtained for each individual by multiplying the impairment percentages by the individual gross wage.

Neck pain intensity, occurence and frequency will be measured based on existing questionnaires (Standardised Nordic questionnaires for the analysis of musculoskeletal Symptoms; Neuromuscular assessment in Elderly Workers with and without work related) (open questions and numeric pain rating scale ranging from 0 to 10).

neck/shoulder trouble).

The German version of the Neck Disability Index (NDI) will be used to evaluate the extent to which NP interferes with vocational, recreational, social, and functional aspects of living. (score from 0 to 100)

Short-form International Physical Activity Questionnaire (IPAQ German version) with data expressed as a continuous variable in metabolic equivalent of task (MET) min per week

The EuroQoL Five Dimension (ordinal scale) and EuroQoL visual analogue scale VAS (0-100 representing worst to best imaginable health state, respectively) will be used.

The Job-Stress-Index provides the ratio between resources and work stressors. Normative statements (percentile ranks) will be given for representative groups of office-workers

Health beliefs will be assessed using three questions of the Fear-Avoidance Beliefs Questionnaire FABQ (dichotomous yes/no variable)

Psychosocial workplace factors will be measured using a questionnaire (Copenhagen Psychosocial Questionnaire)

observation-based ergonomics assessment checklist for office workers is adapted according to Swiss guidelines and used to assess the workplace ergonomics (dichotomous yes/no variable; score)

a single question asking whether the participant felt their workplace culture supported the intervention (dichotomous yes/no variable).

neck and shoulder exercise performance and health promotion session attendance are documented. Next to this, participant's adherence to intervention (workplace ergonomics, exercises, health promotion) is asked using a self-reported scale (ordinal scale)

patients' global impression of change scale (PGIC) is used to reflect the participant's belief about the efficacy of intervention (numeric rating scale ranging from 0 to 10).

Evaluated by two questions:

• "Have you received healthcare services (e.g. doctor, physiotherapist, or other) because of work-related neck trouble in the past 12 months?" (yes/no; what)
• "Have you required pharmaceutical medications due to neck trouble or headache in the last week?" (yes/no; what)

three questions asking about the number of breaks during work, duration of each break (in minutes) and duration of daily smartphone use (in minutes)

single item based on a 10-point numeric rating scale

Movement control dysfunction tests for the cervical spine (dichotomous, positive/negative)

Mobility of the neck and head will be measured by an experienced and trained physiotherapist assessor using a CROM (range of motion, degree)

Muscle endurance (time in seconds to task failure) of neck extensor and flexor muscles will be measured in a standardized testing position, either lying prone for neck extensors or supine for testing neck flexor muscles.

Muscle strength of neck extensor and flexor muscles and shoulder abductor muscles, in Newton peak force will be standardized measured with three repetitions and by using a handheld Dynamometer.

Pain pressure threshold of the upper cervical spine (occiput, atlas) and of the trapezius muscle will be determined by using an Algometer.

Pain drawings: participants will be asked to complete their pain profile during the last week on two body charts (frontal and dorsal views) by using a pen. An operator will instruct the participants to shade their pain experience/complaints. The pain profile will include the aspects of pain extent (expressed as the percentage of the total body chart area where the pain will be reported), pain locations, pain intensity (using a numeric pain rating scale ranging from 0 to 10), location of the most painful spot, and pain intensity of the most painful spot (using a numeric pain rating scale ranging from 0 to 10).

Headache will be measured using the questionnaire "headache impact test" (open questions and numeric pain rating scale ranging from 0 to 10).

Pre-existing headache conditions will be screened for by an adapted headache screening questionnaire, based on validated German questionnaires (German Language Questionnaire for Screening for Migraine, Tension-Type Headache, and Trigeminal Autonomic Cephalgias; German-Language Self-Administered Headache Questionnaire; Der Rostocker Kopfschmerzfragen-Komplex)

(self-reported) including employee's age (in years), sex, body-mass-index BMI (weight (kg) / height (m2)), duration of computer use/day (in minutes), occupation and income range (in CHF), working distance (in minutes, used transport system), general health conditions (diseases, nutrition, health literacy)