Acute neck is very common in the general population and often causes disability over shorter or longer time periods. Unfortunately, the efficacy of chiropractic spinal manipulative therapy (CSMT) and the efficacy of Non-steroidal Anti-inflammatory Drugs (NSAIDs) on acute neck pain is unknown. This 4-arm randomized controlled trial (RCT) will likely provide evidence for the efficacy of CSMT as well as NSAIDs. The applied methodology of the study will aim towards the highest research standards possible for manual-therapy RCTs, thus avoiding typical methodological shortcomings from previous manual-therapy studies. Our aim is to establish evidence-based knowledge on the efficacy of CSMT and NSAIDs in the treatment of acute neck pain.

The Global Burden of Disease study ranks musculoskeletal neck pain as the most common disability worldwide. This study will highlight and validate CSMT for acute neck pain, compared to sham manipulation, ibuprofen and placebo medication. NSAIDs are the most frequently prescribed medications by GPs worldwide and are widely used for patients with back pain. However, evidence-based data are missing for acute neck pain patients treated with NSAIDs while existing evidence for CSMT for acute neck pain are limited by serious methodological shortcomings.

The 4-arm placebo-controlled RCT will assess the efficacy in the following four treatment groups:

1. Chiropractic spinal manipulative therapy (CSMT)
2. CSMT sham manipulation (placebo)
3. Ibuprofen (NSAID)
4. Placebo medication

We intend to invite 40 recruiting chiropractors from larger Norwegian cities, distributed by gender and geography. The study participants presenting to each chiropractor will be block-randomized equally into one of four study groups based on a computer-generated algorithm. Each chiropractor will include 16 participants, four into each arm. A total of 320 participants will be enrolled in the RCT, within 12 months. Participants randomized into the chiropractic treatment groups will receive 5 interventions over 12 days, i.e., CSMT or CSMT sham manipulation; while the pharmacological groups will receive 600mg ibuprofen or placebo administered 3 times daily for 12 days.

Inclusion criteria

1. Eligible participants are between the age of 18 and 59 years old
2. Acute non-radicular neck pain, i.e., grade 1 or 2 according to the classification by the Bone and Joint Decade 2000-2010 Task Force on neck pain
3. Onset of the present episode ≤2 weeks prior to the 1st chiropractic visit
4. Moderate, severe or very severe pain intensity, i.e., ≥4, on a numeric rating scale (NRS) 0-10
5. Pain free for at least four consecutive weeks prior to the present pain episode
6. Not treated by a chiropractor during the past 3 months
7. Participants must accept not to seek other manual and/or pharmacological treatments for their acute neck pain during the intervention period
8. Non-pregnant women. Women in doubt shall have a negative fertility test before inclusion

Exclusion criteria

1. Contraindication to ibuprofen

   1. active peptic ulcer
   2. gastrointestinal bleeding
   3. previous repeated episode (≥2 detected events) with peptic ulcer or gastrointestinal bleeding
   4. previous gastrointestinal bleeding or ulcer using NSAIDs
   5. hypersensitivity to ibuprofen
   6. asthma induced by acetylsalicylic acid or other NSAIDs
   7. urticarial
   8. rhinitis
   9. severe heart failure (NYHA class IV)
   10. renal failure (glomerulus infusion <30 ml/min)

2. Taken pain- and/or anti-inflammatory medicine during the past 24 hours? (Patients that have taken acute pain- and/or anti-inflammatory medicine, including ibuprofen, can be included if they come back after 24 hours without having taken the medicine where they then fill out questionnaires and are randomized at the clinic)

3. On prescribed antidepressant

4. Major psychiatric disorder

5. Pregnancy or intention to be pregnant

6. Contraindication to SMT

7. Signs of spinal radiculopathy including progressive neurological deficit

8. Upper cervical spine instability (positive Sharp-Purser test)

9. Previous fracture in the cervical and/or thoracic spine

10. Previous cervical spine surgery

11. Recent (<6 months) severe physical trauma to the head, neck or thoracic spine within the previous 6 months

12. Concomitant low back pain with moderate, severe or very severe pain intensity (≥4 on a NRS)

13. Current chronic pain (defined as ≥3 months duration)

14. Rheumatoid arthritis

15. Recent (<2 weeks) acute respiratory infection with fever

16. Any presence of ischemic symptoms upon examination

17. Horner's syndrome

18. Medical history of arterial anomalies

19. History of connective tissue disorder

20. Familial history of cervical artery dissection

21. Other vascular disorders

22. Inability to understand instructions given in the Norwegian language

23. Inability to fill out digital questionnaires

24. Other reasons to exclude the patient as deemed necessary by the chiropractor

Participants are blinded. The two chiropractor groups are single-blinded, while the two pharmacological groups are double-blinded. Chiropractor investigators are un-blinded in relation to the manual therapy they apply. Outcome assessors are blinded to group allocation of participants during the study and data analysis.