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. 2023 Nov 21;13(12):1612. doi: 10.3390/brainsci13121612

Table A2.

Stress/anxiety metrics and outcomes of included studies (N = 58) by population and use of stress/anxiety as the primary or secondary outcome. Bolded phrases in “Outcome” column reflect key stress/anxiety intervention outcomes.

Author, Year,
Setting		 Stress/Anxiety Metric Outcomes ** Quality Score, Tool † [62,63]
A. Youth
Youth: Stress/anxiety as primary outcome
* Sellakumar, 2015 [20]
India, secondary school (grades 6–12)		 STAI-state, trait After Ix:

  • Ix but not C had significant decreases in state and trait anxiety (p < 0.001 for both)

  • These reductions were significantly greater in Ix than in C (p < 0.001 for state and trait)

 0.44
(CLEAR)
Poor
* Khng, 2017 [66]
Singapore, 4 elementary schools		 STAI-C-state When doing test after and w/Ix:

  • Ix had significantly greater anxiety reduction vs. C (p = 0.02)

  • Ix had significantly larger increases in math scores (p = 0.04)

 0.57
(CLEAR)
Poor
* Bargale, 2021 [67]
India, hospital pediatric dentistry dept.		 Animated emoji scale

  • From before to after anesthetic procedure, significant anxiety decrease in both groups (p < 0.001) w/no significant differences between groups (p > 0.001)

 0.86
(CLEAR)
Good
Youth: Stress/anxiety as secondary outcome
* Hakked, 2017 [68] India, swim academy SAS-2 From before to after Ix:

  • Ix improved significantly more than C in: max voluntary ventilation (p = 0.02); forced vital capacity (p = 0.026); swim strokes per breath (p = 0.002)

  • Ix but not C significantly improved anxiety (p = 0.031), concentration (p = 0.022), somatic complaints (p = 0.037), inspiratory reserve volume (p < 0.05), and swim strokes per breath (p ≤ 0.001)

 0.69
(CLEAR)
Fair
B. Healthy Adults
Healthy Adults: Stress/anxiety as primary outcome
* Gupta, 2010 [69]
India, yoga training camp		 Sinha Anxiety Scale

  • From before to after Ix, significant decrease in mean anxiety and BDI (p < 0.01) ‡‡

 0.25
(NHLBI)
Poor
* Bhimani, 2011 [31] India, medical college Authors’ 20-item stress questionnaire From before to after Ix:

  • Total stress score significantly decreased (p = 0.0001)

  • Low- and high-frequency HRV showed decreased sympathetic and increased parasympathetic influences and improved sympathovagal balance (p = 0.0001 all)

 0.27
(NHLBI)
Poor
* Sharma, 2013 [70]
India, yoga research center and school 		PSS From baseline to 12 wks:

  • Significant PSS decrease in Ix-1 and Ix-2 (p = 0.000 both)

  • Significant improvement in cardiovascular measures for Ix-2 (p < 0.05) but not Ix-1 (p > 0.09)

 0.66
(CLEAR)
Fair
* Sundram 2014 [71] Malaysia, automotive assembly plant DASS-21 stress subscale 9-mo DASS-21 was significant:

  • Reduced from baseline in Ix and C for all subscales (p < 0.001), and this difference was significantly greater in Ix than C for stress subscale (p < 0.001)

  • Differences between Ix and C (p < 0.001)

 0.62
(NHLBI)
Fair
* Schmalzl, 2018 [72] US, university town PSS

  • Following the 8 wk program, significant:


PSS decrease in Ix and C (p < 0.01)

  • Salivary cortisol decrease in Ix and C (p < 0.01)

  • Improved visual discrimination task in Ix and C (p = 0.017)

  • Improved overall perceptual sensitivity in C (p < 0.01) but not Ix (p > 0.05)

 0.75
(CLEAR)
Fair
* Okado, 2020 [73]
US, university setting		 PSS, GAD-7 From baseline to 2 wks:

  • PSS significantly decreased for Ix-1 (p < 0.01), Ix-2 (p < 0.05), and Ix-3 (p < 005), but not C (p > 0.05)

  • GAD-7 significantly decreased for Ix-1 (p < 0.05)

  • PHQ-15 somatization significantly decreased in Ix-2 (p < 0.05) and Ix-3 (p < 0.05)

  • PHQ-9-M depression significantly decreased for Ix-1 (p < 0.01) and Ix-2 (p < 0.05)

 0.31
(CLEAR)
Poor
* Magnon, 2021 [74]
France, setting unclear		 SAI SAI significantly lower post-Ix among entire group (p < 0.001), young adults (p = 0.003), and older adults (p = 0.019)

  • Significant increase in HF power after Ix (p < 0.001), which was greater in older adults than younger (p = 0.042)

 0.67
(NHLBI)
Fair
* Balban, 2023 [75]
US, remote setting		 STAI

  • Ix-1, Ix-2, and Ix-3 had significant improvement in mood and lower respiratory rate compared w/C (p < 0.05 for all)

  • Averaged over 28 days, all groups significantly reduced state anxiety pre- to post-practice (p < 0.0001 all)

  • No significant change in trait anxiety in any groups, nor differences between groups (p > 0.05)

 0.53
(CLEAR)
Poor
Healthy Adults: Stress/anxiety as secondary outcome
* Busch, 2012 [76]
Germany, university setting		 POMS
tension-
anxiety		 Following Ix:

  • Tension-anxiety significantly improved in Ix-1 and Ix-2 (p < 0.0001)

  • Ix-1 and Ix-2 significantly improved in depression, anger (p < 0.01 all) and total mood disturbances (p < 0.01 Ix, p < 0.05 Ix-2), and not on vigor, fatigue, or confusion scales (p > 0.05 all)

  • No significantly different between Ix-1 and 2 on any POMS measures (p = 0.55)

  • Ix-1 showed significant increases in pain thresholds (p < 0.001) and reductions in sympathetic activity (p = 0.002)

 0.73
(NHBLI)
Fair
Lin, 2014 [45]
Taiwan, university setting		 VAS-anxiety During Ix:

  • Significant differences between all Ix’s for SDNN (p < 0.001), LF (p < 0.001), and LF/HF ratio (p < 0.001), but not HF (p = 0.06)


Using retrospective ratings taken after all Ix’s:

  • Significantly greater relaxation for all compared to baseline (p < 0.05 all)

  • No significant differences in anxiety between any Ix and baseline (p > 0.05 all)

 0.58
(NHLBI)
Poor
* Hunt, 2018 [21]
US, large private university		 10-point Likert scale of subjective stress vs.
relaxation

  • Compared w/C, Ix resulted in significantly higher HRV (p < 0.001), lower respiration rate (p < 0.001), higher tidal volume (p = 0.001), and lower HR (p < 0.001)

  • Stress was significantly lower after Ix and C (p < 0.001 both) than after paced breathing alone

  • No significant stress differences after Ix vs. C (p = 0.14)

  • No significant differences between Ix and C in any outcomes during cognitive stressor challenge (p-value not reported)

 0.56
(CLEAR)
Poor
* Naik, 2018 [77] India, medical school PSS After 12 wks, Ix but not C had significant:

  • Improvements in HR, SBP, DBP (p < 0.05), not BMI and WHR (p > 0.05)

  • Decrease in PSS (p < 0.0001)

  • Compared to C, Ix had greater PSS decrease (p < 0.05)

 0.62
(CLEAR)
Fair
* Conlon, 2022 [78]
UK, University of Bath		 IAMS, 7-point Likert scale of perceived stress

  • No significant Ix effects on shooting performance (p > 0.05)

  • Post-Ix:

  • State anxiety significantly decreased in Ix-1 (p < 0.001) and Ix-2 (p = 0.018) but not C (p > 0.05)

  • Perceived stress significantly decreased in Ix-1 (p < 0.001) and Ix-2 (p = 0.016) but not C (p > 0.05)

 100
(CLEAR)
Good
* Schlatter, 2022 [79]
France, university medical school		 VAS-stress

  • Overall performance was significantly greater in Ix-1 (p = 0.013) and Ix-2 Ix-2 (p = 0.009) vs. C

  • Clinical performance was significantly greater in Ix-1 (p = 0.009) but not Ix-2 (p = 0.073) vs. C

  • No group differences in non-technical skills (p = 0.285)

After the Ix, but before the simulation:

  • VAS-stress significantly lower in Ix-1 (p = 0.029) and Ix-2 (p = 0.035) vs. C, but no differences between Ix’s (p = 0.897)

  • Thayer relaxation significantly lower in Ix-1 (p = 0.0.01) and Ix-2 (p = 0.0.035) vs. C, but no differences between Ix’s (p = 0.709)

  • No differences in Thayer tension between Ix-1 (p = 0.275) and Ix-2 (p = 0.213) vs. C or between Ix’s (p = 0.875)

 0.90
(CLEAR)
Good
C. High-Anxiety Populations
High-Anxiety Populations: Stress/anxiety primary outcome
* Clark, 1990 [80] US, inpatient alcohol rehabilitation facility STAI-state

  • STAI-state anxiety scores and self-reported tension significantly decreased after each session for Ix and C (p < 0.0001 both metrics, groups)

  • Ix had greater improvements than C in STAI-state (p < 0.04) and tension (p < 0.0002)

  • Ix had significantly lower STAI-state scores than C following both sessions (p < 0.01 both)

 0.50
(CLEAR)
Poor
* Chen, 2017 [81]
Taiwan, medical center		 BAI

  • Ix significantly reduced BAI anxiety between wks 0–4 (p = 0.001), 0-8 (p < 0.001), and 4–8 (p < 0.001); C did not (p > 0.05)

  • BAI was significantly lower for Ix than C at wk 8 (p = 0.033)

  • Ix but not C improved significantly from wks 0-8 in skin conductivity (p = 0.48), peripheral temperature (p = 0.007), HR (p < 0.0001), and breathing rate (p < 0.0001)

 0.69
(CLEAR)
Fair
* Serafim, 2018 [82] Brazil, hospital HAM-A, BAI After the Ix and at 10-wk follow-up:

  • HAM-A and BAI were significantly lower (p < 0.001 for both)

  • Depression and mania ratings were significantly lower (p < 0.001 and p = 0.027, respectively)

 0.50
(NHBLI)
Poor
High-Anxiety Populations: Stress/anxiety as secondary outcome
* Clark, 1985 [83] UK, setting unclear 100-pt Likert scale, MMFQ Compared w/before Ix:

  • Panic attack frequency significantly reduced during Ix (p < 0.01) and 2–13 wks after (p < 0.05)

  • Anxiety levels significantly lower (p < 0.01) during 15 min exposure to anxiety-provoking situation

  • Anxiety/depression (p < 0.001) and global distress (p < 0.05) significantly lower

  • No significant changes in BDI depression (p > 0.05)

 0.73
(NHBLI)
Fair
D. Clinical Populations (Acute)
Clinical Populations (Acute): Stress/anxiety as primary outcome
Biggs 2003 [40] US, private dental practice DAR-S

  • No significant differences between any groups overall in dental-related anxiety (p = 0.67), post-Ix anxiety (p = 0.46), or anxiety reduction, including C

  • C participants who used own anxiety reduction technique reported significantly less anxiety (p = 0.04)

 0.38
(CLEAR)
Poor
* Hayama, 2012 [84]
Japan, hospital inpatient		 Short-form POMS (Japanese version)

  • Median post-chemo POMS tension-anxiety significantly lower among Ix vs. C (p = 0.01)

  • Both Ix and C showed significant reductions in pre-post chemo POMS tension-anxiety (both p < 0.01)

 0.69
(CLEAR)
Fair
* Valenza, 2014 [85]
Spain, hospital		 HADS-anxiety

  • Following Ix, all variables were better and improved in Ix, w/significantly improved HADS anxiety, dyspnea, and mobility (p < 0.001 for all) ‡

 0.63
(CLEAR)
Fair
* Bidgoli, 2016 [86]
Iran, hospital		 SAI Compared w/before Ix:

  • Ix but not C had significantly reduced anxiety at 30 and 60 min after Ix (p = 0.0001 both)

  • Anxiety decreases significantly greater in Ix than C (p < 0.05)

 0.53
(CLEAR)
Poor
Boaviagem, 2017 [41]
Brazil, maternity hospital		 STAI (unclear whether state or trait)

  • No differences Ix vs. C in mean STAI (p = 0.58 per-protocol, p = 0.91 ITT)

  • No differences in maternal pain/satisfaction or fatigue; delivery mode; Apgar scores (p > 0.05 all)

 0.75
(CLEAR)
Fair
* Cicek, 2017 [87]
Turkey, hospital delivery room		 STAI-state

  • Mean STAI-state significantly lower (p < 0.001) in Ix vs. C for late active labor but not early or latent (p > 0.05)

  • All labor phases (early latent, late latent, active) except transitional were shorter (p < 0.05) in Ix vs. C

 0.69
(CLEAR)
Fair
* Chandrababu, 2019 [88]
India, hospital 		STAI-state From before surgery to 5th post-op day:

  • STAI-state significantly reduced in Ix (p = 0.001) but not C

  • This reduction was significantly greater in Ix than C (p = 0.001)

  • Ix had significantly less pain than C on 3rd post-op day (p < 0.05)

  • No between-group differences in pain on 4th or 5th days (p > 0.05)

 0.73
(NHLBI)
Fair
Ratcliff, 2019 [47]
US, university medical center		 VAS-anxiety, STAI-state Reduction in VAS anxiety during biopsy was:

  • Significantly greater in Ix-1 than Ix-2 (p < 0.01) and C (p < 0.0001)

  • Not significant differences between Ix-2 and C (p = 0.65)

  • Ix-1 had significant increase in beta current source density (CSD) in insula (p = 0.006) and ACC (p = 0.019) compared to C

 0.64
(CLEAR)
Fair
* Grinberg, 2020 [89]
US, medical center		 STAI-state Compared to C, Ix group had significant:

  • Lower post-procedural STAI-state (p = 0.039)

  • Larger STAI-state decrease pre- to post-procedure (p < 0.000)

  • Lower HR post-procedure (p = 0.048)

  • Larger HR decrease pre- to post-procedure (p = 0.01)

  • No significant BP changes or differences (p > 0.1 all)

 0.50
(NHLBI)
Poor
* Abo El Ata AB, 2021 [90]
Egypt, hospital		 Burn-specific pain anxiety scale Significantly reduced burn-specific pain anxiety:

  • Pre-to-post breathing exercises (p = 0.000)

  • Wk 1 (pre-Ix) to wks 2 and 3 (during Ix; p = 0.000)

From pre- to post-breathing exercises, significantly reduced:

  • Pain (p = 0.000)

  • SBP (p = 0.000), DBP (p = 0.000), respiratory rate (p = 0.000), HR (p = 0.000)

  • From pre-post significantly increased relaxed behavior (p < 0.002)

 0.64
(NHLBI)
Fair
* Hosseinzadeh-Karimkoshteh, 2021 [91]
Iran, medical center		 Burn patient anxiety inventory

  • On each of the 4 days, Ix had significantly lower pain anxiety than C (p < 0.001 all)

 0.78
(CLEAR)
Fair
* Zahn, 2021 [92]
Switzerland, university hospital		 STAI, APAIS,
VAS-stress		 Compared w/C, Ix intraoperative anxiety was:

  • Significantly lower for all measures (STAI-state, p = 0.0001; APAIS, p = 0.0003; VAS, p = 0.0007)

  • Significantly lower vs. pre-op for STAI-state (p = 0.007) and APAIS (p = 0.009), but not VAS (p = 0.79)

 0.64
(CLEAR)
Fair
* Moghadam, 2022 [93]
Iran, psychiatric hospital		 BAI Mean anxiety was significantly lower post-Ix:

  • Compared w/pre-Ix in both Ix’s (p < 0.001) but not C (p = 0.10)

  • In both Ix groups vs. C (p < 0.001)

 0.56
(CLEAR)
Poor
* Aktas, 2023 [39]
Turkey, Ankara Hospital, 		STAI From pre-op to post-Ix:

  • STAI-state significantly decreased in Ix-1 (p = 0.007) but not Ix-2 or C

  • QoL significantly increased in Ix-2 (p = 0.043 both) and C (p = 0.003) but not Ix-1

  • Post-Ix, significantly different in STAI-state across groups (p < 0.05)

 0.37
(CLEAR)
Poor
Clinical Populations (Acute): Stress/anxiety as secondary outcome
* Dhruva, 2012 [94]
US, university medical center		 HADS-anxiety

  • Ix was feasible (close to 100% compliance)

  • Sleep disturbance (p = 0.04) and anxiety (p = 0.04) improved w/every h of

  • pranayama practiced during Ix period

From before-to-after 1st chemo cycle, no significant differences Ix vs. C in stress or other outcomes (p > 0.05 all)		 0.63
(CLEAR)
Fair
* Park, 2013 [95]
South Korea, medical center		 VAS-anxiety Compared w/C and over the 3 days, Ix had significant:

  • Lower pain scores (p = 0.01) and reduction in pain scores (p = 0.001)

  • Lower anxiety (p = 0.01) and reduction in anxiety (p = 0.001)

Ix had significantly reduced anxiety over the 3 days (p = 0.02)		 0.67
(NHLBI)
Fair
* Eldin, 2015 [96]
Libya, hospital		 STAI-state Post-Ix, Ix but not C had significant:

  • STAI decrease all 3 days (p = 0.003 day 1, p < 0.001 days 2 and 3), and decrease was significantly greater than in C (p < 0.001)

  • Pain and pain behavior decreases (p < 0.001 both)

  • Improvement in respiration, HR, and BP (p < 0.001 all)

 0.55
(NHLBI)
Poor
* Iyer, 2020 [97]
India, medical center		 VAS-anxiety, PASS Compared w/pre-Ix, significant decreases found after 1 and 7 days in (p = 0.00 all):

  • Pain

  • Anxiety

  • Anticipatory anxiety

 0.73
(NHLBI)
Fair
* Ursavas, 2020 [98]
Turkey, hospital 		HADS-anxiety At 1,2,4,8,12, and 24 h post-op:

  • Pain: No significant between-group differences at any time point (p > 0.05 all)

  • Compared to C, anxiety significantly lower in Ix (p = 0.033)

  • Depression: No significant differences (p = 0.081)

 0.68
(CLEAR)
Fair
* Lu, 2022 [99]
China, hospital		 HADS Compared w/C, Ix had significant differences in:

  • Dyspnea at T1 (p = 0.037), T3 (p = 0.003)

  • HADS anxiety reductions at T1 day before surgery (p = 0.046), T2, day after surgery (p = 0.02), T3 at discharge (p < 0.001)

  • Post-op complications (p = 0.045)

  • No between-group differences in 6 min walk test times at any time point (p > 0.05)

 0.73
(CLEAR)
Fair
E. Clinical Populations (Chronic)
Clinical Populations (Chronic): Stress/anxiety as primary outcome
* Marshall, 2014 [100]
US, setting unclear		 BAI

  • BAI was significantly lower after 4 wks (p = 0.0069)

  • Among those w/o aphasia, COWAT-measured brain function, and verbal abilities significantly improved after 10 wks (p = 0.0001)

  • Among those w/aphasia, some speech-language measures significantly improved after 4 wks of guided practice (p < 0.05)

 0.55
(NHLBI)
Fair
Clinical Populations (Chronic): Stress/anxiety as secondary outcome
* Han, 1996 [22]
Belgium, setting unclear		 STAI-state and trait

  • From before to after Ix:

HVS complaints significantly reduced (p < 0.001), based on Nijmegen Questionnaire

  • Inspiratory and expiratory time and tidal volume increased significantly (p < 0.001), but not end-tidal CO2 (p > 0.05)

  • State (p < 0.001) but not trait (p > 0.05) anxiety significantly reduced

 0.73
(NHLBI)
Fair
* Thomas, 2009 [101]
UK, primary care general practices		 HADS-anxiety At 6 mo following Ix, Ix had significantly greater improvements than C in AQLQ (p = 0.01), HADS anxiety (p = 0.02), and depression (p = 0.03), and hyperventilation symptoms (p = 0.005)

  • No significant differences between groups in AQLQ, HADS anxiety or depression at 1 mo (p > 0.05 all)

  • Breathing training did not significantly change airway physiology, inflammation, or hyper-responsiveness (p > 0.05 all)

 0.73
(CLEAR)
Fair
Jefferson, 2010 [43]
US, setting unclear		 PSS, STAI

  • SBP and DBP were decreased for Ix at 1-wk follow-up (p = 0.0001 and 0.02, respectively) but not 6 wks, and not for C (p > 0.05)

  • No significant differences after Ix in PSS or STAI-state anxiety for Ix or C (p > 0.05 all)

  • STAI-trait anxiety significantly decreased for Ix (p = 0.01) but not C (p = 0.09) at 1-wk post-Ix, but not at 6 wks (p > 0.05 both)

 0.25
(CLEAR)
Poor
* Sureka, 2014 [102]
India, prison hospital		 PGWBS-anxiety After 6 wks, Ix vs. C had significantly greater improvements in:

  • Global functioning, depression, positive well-being, psychological general well-being, and general health (p < 0.01 for all)

  • PGWBS-anxiety (p < 0.01)

 0.80
(CLEAR)
Fair
* Sureka, 2015 [103]
India, prison hospital		 PGWBS-anxiety After 6 wks, Ix vs. C significantly improved in:

  • GAF (p = 0.0002)

  • Anxiety (p = 0.011)

  • Positive Well-Being (p = 0.02)

  • General Health (p = 0.02)

  • Total PGWB (p = 0.05)

 0.73
(CLEAR)
Fair
Thomas, 2017 [50] UK, general practices HADS-anxiety 12 mo after Ix:

  • AQLQ significantly better in Ix-1 (p < 0.001) and Ix-2 (p < 0.05) vs. C

  • HADS-depression significantly lower in Ix-2 vs. C (p = 0.03)

  • No significant changes in lung function, asthma symptom control, or asthma exacerbation rate vs. C (p > 0.05 all)

  • No significant differences in HADS-anxiety pre-post Ix in all groups or between groups (p > 0.05 all)

 0.80
(CLEAR)
Fair
* Fiskin, 2018 [104]
Turkey, medical center		 DASS After 30 days, Ix had:

  • PAI increase (p = 0.000), greater vs. C (p = 0.000)

  • Stress/anxiety decrease (p = 0.000), greater vs. C (p = 0.000)

  • Depression decrease (p = 0.001), greater vs. C (p = 0.003)

 0.50
(CLEAR)
Poor
* Watson, 2022 [105]
New Zealand hospital		 5-point Likert Scale Compared w/Ix-2, Ix-1 significant initial increase in:

  • QTc interval (p < 0.0002)

  • Anxiety (p < 0.001)

 0.75
(CLEAR)
Fair
F. Simulated Stress
Simulated Stress Populations: Stress/anxiety as primary outcome
Kamath, 2017 [44] India, medical school VAMS-anxiety

  • Ix showed trend (p > 0.05) toward lower VAMS anxiety prior to, during, and following public speaking task

 0.88
(CLEAR)
Good
Simulated Stress Populations: Stress/anxiety as secondary outcome
Holmes, 1978 [42]
US, university setting		 Author-designed 18-item anxiety checklist After threat or stimulation:

  • HR was significantly higher for threat vs. stimulation (p < 0.001), there were no significant differences between groups in stimulation condition, and it was significantly lower for C than Ix-1 or Ix-2 in threat condition (p < 0.05)

  • Skin resistance did not differ between groups or threat/stimulation conditions (p > 0.1)

  • Significantly less anxiety reported in C vs. Ix-1 and Ix-2 (p < 0.05)

  • No significant differences in anxiety between Ix-1 and Ix-2 (p-value not reported)

 0.33
(NHLBI)
Poor
* McCaul, 1979 [106]
US, university setting		 Author-designed 18-item anxiety checklist Following threat/stimulation:

  • Ix-1 anxiety  significantly lower than in combined Ix-2 and Ix-3 (p = 0.03)

  • Self-reported ability to relax while awaiting shock significantly lower in expectation vs. no-expectation groups (p = 0.02)

  • Ix-1 vs. Ix-2 and Ix-3 combined had significantly lower skin resistance and pulse during threat anticipation (p = 0.05, p = 0.02, respectively) and threat (p = 0.02 both), but not HR (p-value not reported)

 0.50
(CLEAR)
Poor
Sakakibara, 1996 [48] Japan, university setting STAI-state Following threat anticipation:

  • High frequency HRV during threat stayed the same for Ix-1 and significantly decreased (worsened) for Ix-2 and C (p < 0.05 for both); low-frequency HRV changes did not differ between groups (p-value not reported)

  • STAI-state anxiety worsened in all groups, w/no differences in changes between groups (p > 0.05)

 0.50
(CLEAR)
Poor
* Telles, 2019 [49]
India, residential yoga center		 STAI-state From pre- to post- each Ix:

  • Shape and size discrimination task errors significantly reduced after Ix-1 (p < 0.001)

  • STAI significantly reduced after Ix-2 (p < 0.05) and C (p < 0.001) but not Ix-1

 0.85
(CLEAR)
Good
Meier, 2020 [46]
Canada, setting unclear		 VAS-stress In response to Ix, no significant differences between groups for cortisol (p = 0.847), alpha amylase (p = 0.735), or stress (p = 0.986)

In response to stressor:

  • Ix-2 had significantly lower cortisol levels vs. C (p = 0.045), but no significant differences for Ix-1 vs. Ix-2 (p = 0.052) or C (p = 0.955)

  • No significant differences between groups for alpha amylase (p = 0.38) or stress (p = 0.818)

 0.81
(CLEAR)
Good
* Sharma, 2022 [107]
India, university setting		 STAI-state From pre- to post-Ix:

  • Significant increase in attention task scores in Ix-4 (p < 0.05)

  • STAI-state scores decreased significantly in Ix-1 (p = 0.001), Ix-2 (p = 0.008), Ix-3 (p = 0.002), Ix-4 (p = 0.042) but not Ix-5 and Ix-6 (p > 0.05)

  • Ix-1 had significantly lower STAI-state scores post-Ix vs. Ix-5 (p < 0.05)

 100
(CLEAR)
Good

Red font indicates an ineffective outcome for stress/anxiety. Bolded phrases in “Outcome” column reflect key stress/anxiety intervention outcomes. Bolded author names/years with asterisk (*) represent studies with at least one intervention that significantly reduced participants’ stress/anxiety. APAIS, Amsterdam Preoperative Anxiety and Information Scale; AQLQ, Asthma Quality of Life Questionnaire; BAI, Beck Anxiety Inventory; BDI, Beck Depression Inventory; BP, blood pressure; C, control; chemo, chemotherapy; COWAT, Controlled Oral Word Association Test; DAR-S, Dental Anxiety Scale Revised; dept, department; GAD-7, Generalized Anxiety Disorder-7; HADS, Hospital Anxiety and Depression Scale; HAM-A, Hamilton Anxiety Rating Scale; HF, high-frequency; h, hour; HR, heart rate; HVS, hyperventilation syndrome; IAMS, Immediate Anxiety Measurement Scale; ITT, intention-to-treat; Ix, intervention; LF, low-frequency; MMFQ, Marks and Matthews Fear Questionnaire; min, minutes; mo, month; PGWBS, Psychological General Well-Being Schedule; PHQ, Patient Health Questionnaire; PMR, progressive muscle relaxation; POMS, Profile of Mood States; PSS, perceived stress scale; pt, point; SAI, State Anxiety Inventory; SAS-2, Sport Anxiety Scale–2; SDNN, standard deviation of the NN intervals; STAI, State-Trait Anxiety Inventory; STAI-C, State-Trait Anxiety Inventory for Children; VAMS, Visual Analog Mood Scale; VAS, Visual Analog Scale; vs., versus; w/, with; w/o, without; wks, weeks * p > 0.05 for impact of breath intervention on psychometric stress outcome. ** Primary outcomes listed first. † Quality scores for RCTs are from the CLEAR-NPT tool for non-pharmaceutical 2+ arm RCTs, with range definitions adopted from Chen 2012: <0.6, poor quality; 0.6–0.8 fair; >0.80 good. Those for non-RCTs are defined based on the National Heart, Lung, and Blood Institute (NHLBI) quality assessment tool’s criteria, with the following author-determined range definitions to be consistent with those from RCTs: <0.6, poor quality; 0.6–0.8 fair; >0.80 good. ‡ The methods and results sections of this paper were found to be poorly written and difficult to interpret. Results reported here represent our best interpretation yet may misrepresent this study’s findings. ‡‡ Textual descriptions of results in paper stated significance, table reported p > 0.01; thus p-value reported here is uncertain.