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Normobaric and hyperbaric oxygen therapy for the treatment and prevention of migraine and cluster headache

Appendices

Appendix 1. Search strategies used for this Cochrane review update

CENTRAL (the Cochrane Library)

#1 MeSH descriptor: [Headache] this term only

#2 MeSH descriptor: [Headache Disorders] explode all trees

#3 (headache* or migrain* or cephalgi* or cephalalgi* or cluster):ti,ab,kw (Word variations have been searched)

#4 #1 or #2 or #3

#5 MeSH descriptor: [Hyperbaric Oxygenation] this term only

#6 MeSH descriptor: [Oxygen Inhalation Therapy] this term only

#7 MeSH descriptor: [Oxygen] this term only and with qualifier(s): [Adverse effects ‐ AE, Therapeutic use ‐ TU, Toxicity ‐ TO]

#8 MeSH descriptor: [Hyperoxia] this term only

#9 MeSH descriptor: [Atmosphere Exposure Chambers] this term only

#10 (hyperbar* or HBO*):ti,ab,kw (Word variations have been searched)

#11 (high pressure oxygen or 100% oxygen):ti,ab,kw (Word variations have been searched)

#12 ((monoplace or multiplace) near/5 chamber*):ti,ab,kw (Word variations have been searched)

#13 #5 or #6 or #7 or #8 or #9 or #10 or #11 or #12

#14 #4 and #13 Publication Date from 2008 to 2015

MEDLINE (OVID)

1. Headache/

2. exp Headache Disorders/

3. (headache$ or migrain$ or cephalgi$ or cephalalgi$ or cluster).tw.

4. or/1‐3

5. Hyperbaric Oxygenation/

6. Oxygen Inhalation Therapy/

7. Oxygen/ae, tu, to

8. Hyperoxia/

9. Atmosphere Exposure Chambers/

10. (hyperbar$ or HBO$).tw.

11. (high pressure oxygen or 100% oxygen).tw.

12. ((monoplace or multiplace) adj5 chamber$).tw.

13. or/5‐12

14. randomized controlled trial.pt.

15. controlled clinical trial.pt.

16. randomized.ab.

17. placebo.ab.

18. drug therapy.fs.

19. randomly.ab.

20. trial.ab.

21. or/14‐20

22. exp animals/ not humans.sh.

23. 21 not 22

24. 4 and 13 and 23

25. (200805* or 200806* or 200807* or 200808* or 200809* or 200810* or 200811* or 200812* or 2009* or 2010* or 2011* or 2012* or 2013* or 2014* or 2015*).

26. 24 and 25

EMBASE (OVID)

1. Headache/

2. exp Headache/ and Facial Pain/

3. (headache$ or migrain$ or cephalgi$ or cephalalgi$ or cluster).tw.

4. or/1‐3

5. Hyperbaric Oxygenation/

6. Oxygen Therapy/

7. Oxygen/ae, tu, to

8. Hyperoxia/

9. Air Quality Control/

10. (hyperbar$ or HBO$).tw.

11. (high pressure oxygen or 100% oxygen).tw.

12. ((monoplace or multiplace) adj5 chamber$).tw.

13. or/5‐12

14. random$.tw.

15. factorial$.tw.

16. crossover$.tw.

17. cross over$.tw.

18. cross‐over$.tw.

19. placebo$.tw.

20. (doubl$ adj blind$).tw.

21. (singl$ adj blind$).tw.

22. assign$.tw.

23. allocat$.tw.

24. volunteer$.tw.

25. Crossover Procedure/

26. double‐blind procedure.tw.

27. Randomized Controlled Trial/

28. Single Blind Procedure/

29. or/14‐28

30. (animal/ or nonhuman/) not human/

31. 29 not 30

32. 4 and 13 and 31

33. (200805* or 200806* or 200807* or 200808* or 200809* or 200810* or 200811* or 200812* or 2009* or 2010* or 2011* or 2012* or 2013* or 2014* or 2015*).dd.

34. 32 and 33

CINAHL (EBSCO)

S24 S14 AND S23

S23 S15 OR S16 OR S17 OR S18 OR S19 OR S20 OR S21 OR S22

S22 (allocat* random*)

S21 (MH "Quantitative Studies")

S20 (MH "Placebos")

S18 (random* allocat*)

S17 (MH "Random Assignment")

S16 (Randomi?ed control* trial*)

S15 (singl* blind* ) or (doubl* blind* ) or (tripl* blind* ) or (trebl* blind* ) or (trebl* mask* ) or (tripl* mask* ) or

(doubl* mask* ) or (singl* mask* )

S14 S12 AND S13

S13 EM 20080501‐20140430

S12 S3 AND S11

S11 S4 OR S5 OR S6 OR S7 OR S8 OR S9 OR S10

S10 ((monoplace or multiplace) N5 (chamber*))

S9 (high pressure oxygen or 100% oxygen)

S8 (hyperbar* or HBO*)

S7 (MH "Hyperoxia")

S6 (MH "Oxygen/AE/TU")

S5 (MH "Oxygen Therapy")

S4 (MH "Hyperbaric Oxygenation")

S3 (S1 OR S2)

S2 (headache* OR migrain* OR cephalgi* OR cephalalgi* OR cluster)

S1 (MH "Headache+")

Appendix 2. Data extraction table for the relief of acute migraine attack

Study ID

Participants and condition

Study design

Treatment

Treatment duration

Outcomes

Data extracted

Fife 1992

14 patients (23 to 67 years, 9 females) with a diagnosis of migraine documented by neurologist evaluation.

Acute therapy trial. RCT with partial cross‐over (patients with relief on first arm could not be crossed) with blinding of patients and investigators. Patients with no relief had the choice of undergoing the second arm of the study 30 minutes after completion of the first arm assigned.

Control: 10% oxygen breathing via Scott mask at 2 ATA.

HBOT: 100% oxygen at 2 ATA on the same schedule.

45 minutes

Proportion of patients with significant pain relief using a Blanchard pain inventory from 0 to 5. Significant relief defined as reduction on this scale of 2 or more points.

Fife 1992 gave the response of all patients from both treatment periods. We have included responders for both initial treatment and on crossover. Total of 8 of 11 individuals obtained pain relief from HBOT and 2 of 7 obtained similar relief from air.

Hill 1992

19 patients with a diagnosis of migraine according to the AHC 1962.

Acute therapy trial. Cross‐over RCT with blinding of patients and investigators. Cross‐over was made 5 minutes after completing the first assigned treatment.

Control: Air breathing at 2.0 ATA.

HBOT: 100% oxygen breathing on the same schedule.

45 minutes

Complete or partial pain relief.

Hill 1992 reported no patients given air and all patients given oxygen obtained some pain relief. (10 had air first and 9 had HBOT first). We included the results given as prior to crossover because of limited reporting. This was a more conservation approach than imputing the response for all crossovers.

Myers 1995

20 patients (14 female) with a diagnosis of migraine confirmed by a physician.

Acute therapy trial. RCT with randomisation not described.

Control: 100% oxygen at 1 ATA for 40 minutes.

HBOT: 100% oxygen breathing using a hood at 2.0 ATA.

40 minutes

Proportion with significant headache relief on a 6 category scale from 'none' to 'most severe ever'.

Myers 1995 reported 9 of 10 patients given HBOT obtained 'total' or 'near‐total' relief of headache versus 1 of the 10 patients given air.

Abbreviations: ATA: atmospheres absolute; HBOT: hyperbaric oxygen therapy; RCT: randomised controlled trial.

Study flow diagram.
Figures and Tables -
Figure 1

Study flow diagram.

'Risk of bias' graph: each 'Risk of bias' item presented as percentages across all included studies.
Figures and Tables -
Figure 2

'Risk of bias' graph: each 'Risk of bias' item presented as percentages across all included studies.

'Risk of bias' summary: review authors' judgements about each 'Risk of bias' item for each included study.
Figures and Tables -
Figure 3

'Risk of bias' summary: review authors' judgements about each 'Risk of bias' item for each included study.

Forest plot of comparison: 1 HBOT versus control for acute migraine attack, outcome: 1.1 Substantial acute relief of headache.
Figures and Tables -
Figure 4

Forest plot of comparison: 1 HBOT versus control for acute migraine attack, outcome: 1.1 Substantial acute relief of headache.

Comparison 1 HBOT versus control for acute migraine attack, Outcome 1 Substantial acute relief of headache.
Figures and Tables -
Analysis 1.1

Comparison 1 HBOT versus control for acute migraine attack, Outcome 1 Substantial acute relief of headache.

Summary of findings for the main comparison. Hyperbaric oxygen therapy for acute migraine

Hyperbaric oxygen therapy for the relief of acute migraine

Patient or population: Acute migraine
Setting: Hospital care
Intervention: HBOT (2.0 to 2.4 ATA for 40 to 45 minutes)
Comparison: Sham therapy (air at pressure or 100% oxygen at 1 ATA)

Outcomes

Anticipated absolute effects* (95% CI)

Relative effect
(95% CI)

Number of participants
(trials)

Quality of the evidence
(GRADE)

Comments

Risk with sham therapy

Risk with HBOT

Chance of obtaining substantial headache relief (Relief).
Assessed with: Patient self‐assessment

Study population

RR 6.21
(2.41 to 16.00)

58
(3 RCTs)

Low¹

We included 3 small RCTs but all showed large effect size with HBOT compared to either air or 100% oxygen sham.

111 per 1000

663 per 1000
(162 to 1000)

*The risk in the intervention group (and its 95% CI) is based on the assumed risk in the comparison group and the relative effect of the intervention (and its 95% CI).
Abbreviations: CI: confidence interval; RR: risk ratio; OR: odds ratio; ATA: atmospheres absolute; HBOT: hyperbaric oxygen therapy.

GRADE Working Group grades of evidence
High quality: We are very confident that the true effect lies close to that of the estimate of the effect.
Moderate quality: We are moderately confident in the effect estimate: The true effect is likely to be close to the estimate of the effect, but there is a possibility that it is substantially different.
Low quality: Our confidence in the effect estimate is limited: The true effect may be substantially different from the estimate of the effect.
Very low quality: We have very little confidence in the effect estimate: The true effect is likely to be substantially different from the estimate of effect.

¹The evidence has been downgraded from moderate to low due to two of these trials being incompletely reported crossover trials reported only in abstract. [Two of the three included studies were planned as crossover trials. In those two, many patients obtained relief during the first treatment period and were not crossed to the second period. For Hill 1992, where all patients are not clearly accounted for we have included the results only from the first treatment period.]

Figures and Tables -
Summary of findings for the main comparison. Hyperbaric oxygen therapy for acute migraine
Comparison 1. HBOT versus control for acute migraine attack

Outcome or subgroup title

No. of studies

No. of participants

Statistical method

Effect size

1 Substantial acute relief of headache Show forest plot

3

58

Risk Ratio (M‐H, Fixed, 95% CI)

6.21 [2.41, 16.00]

1.1 HBOT versus air sham therapy

2

38

Risk Ratio (M‐H, Fixed, 95% CI)

5.28 [1.76, 15.87]

1.2 HBOT versus 100% oxygen at 1 ATA

1

20

Risk Ratio (M‐H, Fixed, 95% CI)

9.0 [1.39, 58.44]

Figures and Tables -
Comparison 1. HBOT versus control for acute migraine attack