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Psychological interventions using virtual reality for pain associated with medical procedures: a systematic review and meta-analysis

Published online by Cambridge University Press:  28 August 2019

Raluca Georgescu ,
Liviu A. Fodor ,
Anca Dobrean  and
Ioana A. Cristea Open the ORCID record for Ioana A. Cristea [Opens in a new window]
Raluca Georgescu
Affiliation:
International Institute for The Advanced Studies of Psychotherapy and Applied Mental Health, Babeș-Bolyai University, Cluj-Napoca, Romania Evidence Based Psychological Assessment and Interventions Doctoral School, Babeș-Bolyai University, Cluj-Napoca, Romania
Liviu A. Fodor
Affiliation:
International Institute for The Advanced Studies of Psychotherapy and Applied Mental Health, Babeș-Bolyai University, Cluj-Napoca, Romania Evidence Based Psychological Assessment and Interventions Doctoral School, Babeș-Bolyai University, Cluj-Napoca, Romania
Anca Dobrean
Affiliation:
International Institute for The Advanced Studies of Psychotherapy and Applied Mental Health, Babeș-Bolyai University, Cluj-Napoca, Romania Department of Clinical Psychology and Psychotherapy, Babeş-Bolyai University, Republicii Street 37, 400015, Cluj-Napoca, Romania
Ioana A. Cristea*
Affiliation:
Department of Clinical Psychology and Psychotherapy, Babeş-Bolyai University, Republicii Street 37, 400015, Cluj-Napoca, Romania Department of Clinical, Neuro and Developmental Psychology, Vrije Universiteit, Amsterdam, The Netherlands
*
Author for correspondence: Ioana A. Cristea, E-mail: [email protected]
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Abstract

Background

Virtual reality (VR) may enhance the effectiveness of psychological interventions for acute pain. We conducted a meta-analysis to assess the efficacy and safety of VR-based interventions for pain associated with medical procedures.

Methods

We searched PubMed, EMBASE, the Cochrane Library, and PsycINFO until June 17th 2018. We identified randomized controlled trials (RCTs), comparing VR-based psychological interventions to usual care, for pain intensity (primary outcome) or affective and cognitive components of pain (secondary outcomes), assessed real-time or retrospectively. Two independent reviewers performed study selection and data extraction. Risk of bias was independently evaluated by three raters using the revised Cochrane Collaboration tool. A random-effects model using the Paule and Mandel estimator was used for pooling effect sizes.

Results

27 RCTs (1452 patients) provided enough data for meta-analysis. Compared to usual care, VR-based interventions reduced pain intensity both real-time (9 RCTs, Hedges' g = 0.95, 95% CI 0.32–1.57) and retrospectively (22 RCTs, g = 0.87, 95% CI 0.54–1.21). Results were similar for cognitive (8 RCTs, g = 0.82, 95% CI 0.39–1.26) and affective pain components (14 RCTs, g = 0.55, 95% CI 0.34–0.77). There was marked heterogeneity, which remained similarly high in sensitivity analyses. Across domains, few trials were rated as low risk of bias and there was evidence of publication bias. Adverse events were rare.

Conclusions

Though VR-based interventions reduced pain for patients undergoing medical procedures, inferring clinical effectiveness is precluded by the predominance of small trials, with substantial risk of bias, and by incomplete reporting.

Keywords

Acute painmedical procedureprocedural painpsychological interventionvirtual realitymeta-analysis
Type
Original Articles
Information
Psychological Medicine , Volume 50 , Issue 11 , August 2020 , pp. 1795 - 1807
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Copyright
Copyright © Cambridge University Press 2019

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References

Barr, J, Fraser, GL, Puntillo, K, Ely, EW, Gélinas, C, Dasta, JF, Davidson, JE, Devlin, JW, Kress, JP, Joffe, AM, Coursin, DB, Herr, DL, Tung, A, Robinson, BRH, Fontaine, DK, Ramsay, MA, Riker, RR, Sessler, CN, Pun, B, Skrobik, Y and Jaeschke, R and American College of Critical Care Medicine (2013) Clinical practice guidelines for the management of pain, agitation, and delirium in adult patients in the intensive care unit. Critical Care Medicine 41, 263–306.CrossRefGoogle ScholarPubMed
Bentsen, B, Svensson, P and Wenzel, A (2001) Evaluation of effect of 3D video glasses on perceived pain and unpleasantness induced by restorative dental treatment. European Journal of Pain (London, England) 5, 373–378.CrossRefGoogle ScholarPubMed
Birnie, KA, Noel, M, Parker, JA, Chambers, CT, Uman, LS, Kisely, SR and McGrath, PJ (2014) Systematic review and meta-analysis of distraction and hypnosis for needle-related pain and distress in children and adolescents. Journal of Pediatric Psychology 39, 783–808.CrossRefGoogle ScholarPubMed
Borenstein, M, Hedges, LV, Higgins, JPT and Rothstein, HR (2009) Introduction to meta-analysis. In Statistics in Practice, 1st Edn. West Sussex, UK: Wiley & Sons Ltd, pp. 21–32.Google Scholar
Breivik, H, Eisenberg, E and O'Brien, T and OPENMinds (2013) The individual and societal burden of chronic pain in Europe: the case for strategic prioritisation and action to improve knowledge and availability of appropriate care. BMC Public Health 13, 1229.CrossRefGoogle ScholarPubMed
Brooks, FP (1999) What's real about virtual reality? IEEE Computer Graphics and Applications 19, 16–27.CrossRefGoogle Scholar
Brown, NJ, Kimble, RM, Rodger, S, Ware, RS and Cuttle, L (2014) Play and heal: randomized controlled trial of DittoTM intervention efficacy on improving re-epithelialization in pediatric burns. Burns 40, 204–213.CrossRefGoogle ScholarPubMed
Carrougher, GJ, Hoffman, HG, Nakamura, D, Lezotte, D, Soltani, M, Leahy, L, Engrav, LH and Patterson, DR (2009) The effect of virtual reality on pain and range of motion in adults with burn injuries. Journal of burn care & research: official publication of the American Burn Association 30, 785–791.CrossRefGoogle ScholarPubMed
Chan, EY, Blyth, FM, Nairn, L and Fransen, M (2013) Acute postoperative pain following hospital discharge after total knee arthroplasty. Osteoarthritis and Cartilage 21, 1257–1263.CrossRefGoogle ScholarPubMed
Chan, EA, Chung, JW, Wong, TK, Lien, AS and Yang, JY (2007) Application of a virtual reality prototype for pain relief of pediatric burn in Taiwan. Journal of Clinical Nursing 16, 786–793.CrossRefGoogle ScholarPubMed
Chan, E, Foster, S, Sambell, R and Leong, P (2018) Clinical efficacy of virtual reality for acute procedural pain management: a systematic review and meta-analysis. PloS One 13, e0200987.CrossRefGoogle ScholarPubMed
da Costa, RSM, do Ribeiro, SN and Cabral, ED (2012) Determinants of painful experience during dental treatment. Revista Dor 13, 365–370.Google Scholar
Delshad, SD, Almario, CV, Fuller, G, Luong, D and Spiegel, BMR (2018) Economic analysis of implementing virtual reality therapy for pain among hospitalized patients. NPJ Digital Medicine 1, 22.CrossRefGoogle ScholarPubMed
Doi, SAR, Barendregt, JJ, Khan, S, Thalib, L and Williams, GM (2015) Advances in the meta-analysis of heterogeneous clinical trials II: the quality effects model. Contemporary Clinical Trials 45, 123–129.CrossRefGoogle ScholarPubMed
Egger, M, Davey Smith, G, Schneider, M and Minder, C (1997) Bias in meta-analysis detected by a simple, graphical test. BMJ (Clinical Research ed.) 315, 629–634.CrossRefGoogle ScholarPubMed
Elbourne, DR, Altman, DG, Higgins, JPT, Curtin, F, Worthington, HV and Vail, A (2002) Meta-analyses involving cross-over trials: methodological issues. International Journal of Epidemiology 31, 140–149.CrossRefGoogle ScholarPubMed
Fisher, DJ (2015) Two-stage individual participant data meta-analysis and generalized forest plots. The Stata Journal 15, 369–396.CrossRefGoogle Scholar
Fisher, D (2019) ADMETAN: Stata Module to Provide Comprehensive Meta-Analysis. Boston College Department of Economics, Boston.Google Scholar
Frere, CL, Crout, R, Yorty, J and McNeil, DW (2001) Effects of audiovisual distraction during dental prophylaxis. Journal of the American Dental Association (1939) 132, 1031–1038.Google Scholar
Gallace, A, Ngo, MK, Sulaitis, J and Spence, C (2012) Multisensory presence in virtual reality: possibilities & limitations. In Ghinea, G, Andres, F and Gulliver, S (eds), Multiple sensorial media advances and applications: new developments in MulSeMedia. Hershey: IGI Global; Hershey, Pennsylvania.Google Scholar
Gerçeker, GÖ, Binay, Ş, Bilsin, E, Kahraman, A and Yılmaz, HB (2018) Effects of virtual reality and external cold and vibration on pain in 7- to 12-year-Old children during phlebotomy: a randomized controlled trial. Journal of Perianesthesia Nursing: Official Journal of the American Society of PeriAnesthesia Nurses 6, 981–989.CrossRefGoogle Scholar
Gershon, J, Zimand, E, Pickering, M, Rothbaum, BO and Hodges, L (2004) A pilot and feasibility study of virtual reality as a distraction for children with cancer. Journal of the American Academy of Child and Adolescent Psychiatry 43, 1243–1249.CrossRefGoogle ScholarPubMed
Gold, JI, Belmont, KA and Thomas, DA (2007) The neurobiology of virtual reality pain attenuation. CyberPsychology & Behavior 10, 536–544.CrossRefGoogle ScholarPubMed
Gold, JI, Kim, SH, Kant, AJ, Joseph, MH and Rizzo, AS (2006) Effectiveness of virtual reality for pediatric pain distraction during i.v. placement. Cyberpsychology & Behavior: The Impact of the Internet, Multimedia and Virtual Reality on Behavior and Society 9, 207–212.CrossRefGoogle ScholarPubMed
Gold, JI and Mahrer, NE (2018) Is virtual reality ready for prime time in the medical space? A randomized control trial of pediatric virtual reality for acute procedural pain management. Journal of Pediatric Psychology 43, 266–275.CrossRefGoogle ScholarPubMed
Guo, C, Deng, H and Yang, J (2015) Effect of virtual reality distraction on pain among patients with hand injury undergoing dressing change. Journal of Clinical Nursing 24, 115–120.CrossRefGoogle ScholarPubMed
Harbord, RM, Harris, RJ and Sterne, JAC (2009) Updated tests for small-study effects in meta-analyses. The Stata Journal 9, 197–210.CrossRefGoogle Scholar
Hartung, J and Knapp, G (2001) On tests of the overall treatment effect in meta-analysis with normally distributed responses. Statistics in Medicine 20, 1771–1782.CrossRefGoogle ScholarPubMed
Hedges, LV and Olkin, I (1985) Statistical Methods for Meta-Analysis. San Diego, CA: Academic Press.Google Scholar
Henmi, M and Copas, JB (2010) Confidence intervals for random effects meta-analysis and robustness to publication bias. Statistics in Medicine 29, 2969–2983.CrossRefGoogle ScholarPubMed
Higgins, I and Green, S (2011) Cochrane Handbook for Systematic Reviews of Interventions Version 5.1.0 [updated March 2011].Google Scholar
Higgins, JPT, Thompson, SG, Deeks, JJ and Altman, DG (2003) Measuring inconsistency in meta-analyses. BMJ (Clinical Research ed.) 327, 557–560.CrossRefGoogle ScholarPubMed
Higgins, JPT, Thompson, SG and Spiegelhalter, DJ (2009) A re-evaluation of random-effects meta-analysis. Journal of the Royal Statistical Society. Series A, (Statistics in Society) 172, 137–159.CrossRefGoogle ScholarPubMed
Higgins, JPT, Sterne, J, Savović, J, Page, M, Hróbjartsson, A, Boutron, I, Reeves, B and Eldridge, S (2016) A revised tool for assessing risk of bias in randomized trials. Cochrane Methods Cochrane Database of Systematic Reviews 2016.Google Scholar
Hoffman, HG, Patterson, DR and Carrougher, GJ (2000) Use of virtual reality for adjunctive treatment of adult burn pain during physical therapy: a controlled study. The Clinical Journal of Pain 16, 244–250.CrossRefGoogle ScholarPubMed
Hoffman, HG, Patterson, DR, Carrougher, GJ and Sharar, SR (2001) Effectiveness of virtual reality-based pain control with multiple treatments. The Clinical Journal of Pain 17, 229–235.CrossRefGoogle ScholarPubMed
Hoffman, HG, Patterson, DR, Seibel, E, Soltani, M, Jewett-Leahy, L and Sharar, SR (2008) Virtual reality pain control during burn wound debridement in the hydrotank. The Clinical Journal of Pain 24, 299–304.CrossRefGoogle ScholarPubMed
Hua, Y, Qiu, R, Yao, W-Y, Zhang, Q and Chen, X-L (2015) The Effect of Virtual Reality Distraction on Pain Relief During Dressing Changes in Children with Chronic Wounds on Lower Limbs. Pain Management Nursing: Official Journal of the American Society of Pain Management Nurses 16, 685–691.CrossRefGoogle ScholarPubMed
Ioannidis, JPA, Patsopoulos, NA and Evangelou, E (2007) Uncertainty in heterogeneity estimates in meta-analyses. BMJ (Clinical Research ed.) 335, 914–916.CrossRefGoogle ScholarPubMed
Jackson, D and Bowden, J (2016) Confidence intervals for the between-study variance in random-effects meta-analysis using generalised heterogeneity statistics: should we use unequal tails? BMC Medical Research Methodology 16, 55–79.CrossRefGoogle ScholarPubMed
JahaniShoorab, N, Ebrahimzadeh Zagami, S, Nahvi, A, Mazluom, SR, Golmakani, N, Talebi, M and Pabarja, F (2015) The effect of virtual reality on pain in primiparity women during episiotomy repair: a randomize clinical trial. Iranian Journal of Medical Sciences 40, 219–224.Google ScholarPubMed
Jeffs, D, Dorman, D, Brown, S, Files, A, Graves, T, Kirk, E, Meredith-Neve, S, Sanders, J, White, B and Swearingen, CJ (2014) Effect of virtual reality on adolescent pain during burn wound care. Journal of Burn Care & Research: Official Publication of the American Burn Association 35, 395–408.CrossRefGoogle ScholarPubMed
Kipping, B, Rodger, S, Miller, K and Kimble, RM (2012) Virtual reality for acute pain reduction in adolescents undergoing burn wound care: a prospective randomized controlled trial. Burns: Journal of the International Society for Burn Injuries 38, 650–657.CrossRefGoogle ScholarPubMed
Kleiber, C and Harper, DC (1999) Effects of distraction on children's pain and distress during medical procedures: a meta-analysis. Nursing Research 48, 44–49.CrossRefGoogle ScholarPubMed
Konstantatos, AH, Angliss, M, Costello, V, Cleland, H and Stafrace, S (2009) Predicting the effectiveness of virtual reality relaxation on pain and anxiety when added to PCA morphine in patients having burns dressings changes. Burns: Journal of the International Society for Burn Injuries 35, 491–499.CrossRefGoogle ScholarPubMed
Kraemer, HC and Kupfer, DJ (2006) Size of treatment effects and their importance to clinical research and practice. Biological Psychiatry 59, 990–996.CrossRefGoogle ScholarPubMed
Laupacis, A, Sackett, DL and Roberts, RS (1988) An assessment of clinically useful measures of the consequences of treatment. The New England Journal of Medicine 318, 1728–1733.CrossRefGoogle ScholarPubMed
Li, L, Yu, F, Shi, D, Shi, J, Tian, Z, Yang, J, Wang, X and Jiang, Q (2017) Application of virtual reality technology in clinical medicine. American Journal of Translational Research 9, 3867–3880.Google ScholarPubMed
Maani, CV, Hoffman, HG, Morrow, M, Maiers, A, Gaylord, K, McGhee, LL and DeSocio, PA (2011) Virtual reality pain control during burn wound debridement of combat-related burn injuries using robot-like arm mounted VR goggles. The Journal of Trauma 71, S125–S130.CrossRefGoogle ScholarPubMed
Malloy, KM and Milling, LS (2010) The effectiveness of virtual reality distraction for pain reduction: a systematic review. Clinical Psychology Review 30, 1011–1018.CrossRefGoogle ScholarPubMed
Miller, K, Rodger, S, Bucolo, S, Greer, R and Kimble, RM (2010) Multi-modal distraction. Using technology to combat pain in young children with burn injuries. Burns: Journal of the International Society for Burn Injuries 36, 647–658.CrossRefGoogle ScholarPubMed
Miller, K, Rodger, S, Kipping, B and Kimble, RM (2011) A novel technology approach to pain management in children with burns: a prospective randomized controlled trial. Burns: Journal of the International Society for Burn Injuries 37, 395–405.CrossRefGoogle ScholarPubMed
Moher, D, Liberati, A, Tetzlaff, J and Altman, DG and PRISMA Group (2009) Preferred reporting items for systematic reviews and meta-analyses: the PRISMA statement. PLoS Medicine 6, e1000097.CrossRefGoogle ScholarPubMed
Morris, LD, Louw, QA and Crous, LC (2010) Feasibility and potential effect of a low-cost virtual reality system on reducing pain and anxiety in adult burn injury patients during physiotherapy in a developing country. Burns: Journal of the International Society for Burn Injuries 36, 659–664.CrossRefGoogle ScholarPubMed
Norman, AT and Judkins, KC (2004) Pain in the patient with burns. Continuing Education in Anaesthesia Critical Care & Pain 4, 57–61.CrossRefGoogle Scholar
Pak, JG and White, SN (2011) Pain prevalence and severity before, during, and after root canal treatment: a systematic review. Journal of Endodontics 37, 429–438.CrossRefGoogle ScholarPubMed
Palmer, TM, Sutton, AJ, Peters, JL and Moreno, SG (2008) Contour-enhanced funnel plots for meta-analysis. The Stata Journal: Promoting communications on statistics and Stata 8, 242–254.CrossRefGoogle Scholar
Paule, RC and Mandel, J (1982) Consensus values and weighting factors. Journal of Research of the National Bureau of Standards 87, 377.CrossRefGoogle Scholar
Peters, JL, Sutton, AJ, Jones, DR, Abrams, KR and Rushton, L (2008) Contour-enhanced meta-analysis funnel plots help distinguish publication bias from other causes of asymmetry. Journal of Clinical Epidemiology 61, 991–996.CrossRefGoogle ScholarPubMed
Piskorz, J and Czub, M (2014) Distraction of attention with the use of virtual reality. Influence of the level of game complexity on the level of experienced pain. Polish Psychological Bulletin 45, 480–487.CrossRefGoogle Scholar
Röver, C, Knapp, G and Friede, T (2015) Hartung-Knapp-Sidik-Jonkman approach and its modification for random-effects meta-analysis with few studies. BMC Medical Research Methodology 15, 99.CrossRefGoogle ScholarPubMed
Scheffler, M, Koranyi, S, Meissner, W, Strauß, B and Rosendahl, J (2017) Efficacy of non-pharmacological interventions for procedural pain relief in adults undergoing burn wound care: a systematic review and meta-analysis of randomized controlled trials. Burns: Journal of the International Society for Burn Injuries 7, 1709–1720.Google Scholar
Schmitt, YS, Hoffman, HG, Blough, DK, Patterson, DR, Jensen, MP, Soltani, M, Carrougher, GJ, Nakamura, D and Sharar, SR (2011) A randomized, controlled trial of immersive virtual reality analgesia, during physical therapy for pediatric burns. Burns: Journal of the International Society for Burn Injuries 37, 61–68.CrossRefGoogle ScholarPubMed
Schneider, SM, Ellis, M, Coombs, WT, Shonkwiler, EL and Folsom, LC (2003) Virtual reality intervention for older women with breast cancer. Cyberpsychology & Behavior: The Impact of the Internet, Multimedia and Virtual Reality on Behavior and Society 6, 301–307.CrossRefGoogle ScholarPubMed
Schneider, SM, Prince-Paul, M, Allen, MJ, Silverman, P and Talaba, D (2004) Virtual reality as a distraction intervention for women receiving chemotherapy. Oncology Nursing Forum 31, 81–88.CrossRefGoogle ScholarPubMed
Seers, K and Carroll, D (1998) Relaxation techniques for acute pain management: a systematic review. Journal of Advanced Nursing 27, 466–475.CrossRefGoogle ScholarPubMed
Sidik, K and Jonkman, JN (2002) A simple confidence interval for meta-analysis. Statistics in Medicine 21, 3153–3159.CrossRefGoogle ScholarPubMed
Sommer, M, de Rijke, JM, van Kleef, M, Kessels, AGH, Peters, ML, Geurts, JWJM, Gramke, H-F and Marcus, MAE (2008) The prevalence of postoperative pain in a sample of 1490 surgical inpatients. European Journal of Anaesthesiology 25, 267–274.CrossRefGoogle Scholar
Torrati, FG, Rossi, LA, Ferreira, E, Dalri, MC, de Carvalho, EC and dos Santos Barbeira, CB (2000) Analysis of cost of dressings in the care of burn patients. Burns: Journal of the International Society for Burn Injuries 26, 289–293.CrossRefGoogle ScholarPubMed
Tsirigotou, S (1993) Acute and chronic pain resulting from burn injuries. Annals of the Mediterranean Burns Club 6, 1.Google Scholar
Turk, DC and Okifuji, A (2002) Psychological factors in chronic pain: evolution and revolution. Journal of Consulting and Clinical Psychology 70, 678–690.CrossRefGoogle ScholarPubMed
Uman, LS, Chambers, CT, McGrath, PJ and Kisely, S (2008) A systematic review of randomized controlled trials examining psychological interventions for needle-related procedural pain and distress in children and adolescents: an abbreviated cochrane review. Journal of Pediatric Psychology 33, 842–854.CrossRefGoogle ScholarPubMed
van den Beuken-van Everdingen, MHJ, Hochstenbach, LMJ, Joosten, EAJ, Tjan-Heijnen, VCG and Janssen, DJA (2016) Update on prevalence of pain in patients with cancer: systematic review and meta-analysis. Journal of Pain and Symptom Management 51, 1070–1090.e9.CrossRefGoogle ScholarPubMed
Verhoeven, K, Crombez, G, Eccleston, C, Van Ryckeghem, DML, Morley, S and Van Damme, S (2010) The role of motivation in distracting attention away from pain: an experimental study. Pain 149, 229–234.CrossRefGoogle ScholarPubMed
Verhoeven, K, Dick, B, Eccleston, C, Goubert, L and Crombez, G (2014) The role of executive functioning in children's attentional pain control: an experimental analysis. Pain 155, 413–421.CrossRefGoogle ScholarPubMed
Veroniki, AA, Jackson, D, Viechtbauer, W, Bender, R, Bowden, J, Knapp, G, Kuss, O, Higgins, JP, Langan, D and Salanti, G (2016) Methods to estimate the between-study variance and its uncertainty in meta-analysis. Research Synthesis Methods 7, 55–79.CrossRefGoogle ScholarPubMed
Viechtbauer, W (2007) Confidence intervals for the amount of heterogeneity in meta-analysis. Statistics in Medicine 26, 37–52.CrossRefGoogle ScholarPubMed
Walker, MR, Kallingal, GJS, Musser, JE, Folen, R, Stetz, MC and Clark, JY (2014) Treatment efficacy of virtual reality distraction in the reduction of pain and anxiety during cystoscopy. Military Medicine 179, 891–896.CrossRefGoogle ScholarPubMed
Wint, SS, Eshelman, D, Steele, J and Guzzetta, CE (2002) Effects of distraction using virtual reality glasses during lumbar punctures in adolescents with cancer. Oncology Nursing Forum 29, E8–E15.CrossRefGoogle Scholar
Wolitzky, K, Fivush, R, Zimand, E, Hodges, L and Rothbaum, BO (2005) Effectiveness of virtual reality distraction during a painful medical procedure in pediatric oncology patients. Psychology & Health 20, 817–824.CrossRefGoogle Scholar
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