{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,10,1]],"date-time":"2026-10-01T05:49:27Z","timestamp":1790833767073,"version":"4.1.0"},"reference-count":40,"publisher":"Springer Science and Business Media LLC","issue":"1","license":[{"start":{"date-parts":[[2021,10,20]],"date-time":"2021-10-20T00:00:00Z","timestamp":1634688000000},"content-version":"tdm","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0"},{"start":{"date-parts":[[2021,10,20]],"date-time":"2021-10-20T00:00:00Z","timestamp":1634688000000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0"}],"content-domain":{"domain":["link.springer.com"],"crossmark-restriction":false},"short-container-title":["BMC Musculoskelet Disord"],"published-print":{"date-parts":[[2021,12]]},"abstract":"<jats:title>Abstract<\/jats:title><jats:sec>\n                <jats:title>Background<\/jats:title>\n                <jats:p>Research is often undertaken using patient-reported outcomes from questionnaires. Achieving a high response rate demands expensive and time-consuming methods like telephone reminders. However, it is unknown whether telephone reminders change outcome estimates or only affect the response rate in research of populations with low back pain (LBP). The aim is to compare baseline characteristics and the change in outcome between patients responding before and after receiving a telephone reminder.<\/jats:p>\n              <\/jats:sec><jats:sec>\n                <jats:title>Methods<\/jats:title>\n                <jats:p>This is an ancillary analysis of data from a prospective cohort study employing questionnaires from 812 adults with LBP lasting more than 3\u2009months. Patients not responding to the 52-week questionnaire were sent reminder emails after two and 3 weeks and delivered postal reminders after 4 weeks. Patients still not responding were contacted by telephone, with a maximum of two attempts. Patients were categorised into three groups: 1) patients responding before a telephone reminder was performed; 2) patients responding after the telephone reminder and 3) patients not responding at all. A positive outcome was defined as a 30% improvement on the Roland Morris Disability Questionnaire after 52\u2009weeks.<\/jats:p>\n              <\/jats:sec><jats:sec>\n                <jats:title>Results<\/jats:title>\n                <jats:p>A total of 695 patients (85.2%) responded. Of these, 643 patients were classified in Group 1 and 52 patients were classified in Group 2. One hundred seventeen were classified in Group 3. No differences in outcome or baseline characteristics was found. In Group 1, 41.3% had a positive outcome, and in Group 2 48.9% had a positive outcome (<jats:italic>P<\/jats:italic>\u2009=\u20090.297). In group 3, non-respondents were younger, more often unemployed, more often smokers, more often reported co-morbidity, and reported higher depression scores than respondents.<\/jats:p>\n              <\/jats:sec><jats:sec>\n                <jats:title>Conclusions<\/jats:title>\n                <jats:p>Using a telephone reminder had no consequence on outcome estimates nor were there any differences in baseline characteristics between patients who responded before or after the telephone reminder.<\/jats:p>\n              <\/jats:sec><jats:sec>\n                <jats:title>Trial registration<\/jats:title>\n                <jats:p>The initial trial was registered in <jats:ext-link xmlns:xlink=\"http:\/\/www.w3.org\/1999\/xlink\" ext-link-type=\"uri\" xlink:href=\"http:\/\/clinicaltrials.gov\">Clinicaltrials.gov<\/jats:ext-link> (<jats:ext-link xmlns:xlink=\"http:\/\/www.w3.org\/1999\/xlink\" ext-link-type=\"uri\" xlink:href=\"https:\/\/clinicaltrials.gov\/ct2\/show\/NCT03058315?term=NCT03058315&amp;draw=2&amp;rank=1\">NCT03058315<\/jats:ext-link>).<\/jats:p>\n              <\/jats:sec>","DOI":"10.1186\/s12891-021-04787-4","type":"journal-article","created":{"date-parts":[[2021,10,20]],"date-time":"2021-10-20T17:47:54Z","timestamp":1634752074000},"update-policy":"https:\/\/doi.org\/10.1007\/springer_crossmark_policy","source":"Crossref","is-referenced-by-count":5,"title":["Does the use of telephone reminders to increase survey response rates affect outcome estimates? An ancillary analysis of a prospective cohort study of patients with low back pain"],"prefix":"10.1186","volume":"22","author":[{"given":"Christina Lyngs\u00f8","family":"Udby","sequence":"first","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Allan","family":"Riis","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Janus Laust","family":"Thomsen","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Nanna","family":"Rolving","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"297","published-online":{"date-parts":[[2021,10,20]]},"reference":[{"issue":"10137","key":"4787_CR1","doi-asserted-by":"publisher","first-page":"2368","DOI":"10.1016\/S0140-6736(18)30489-6","volume":"391","author":"NE Foster","year":"2018","unstructured":"Foster NE, Anema JR, Cherkin D, Chou R, Cohen SP, Gross DP, et al. Prevention and treatment of low back pain: evidence, challenges, and promising directions. Lancet. 2018;391(10137):2368\u201383.","journal-title":"Lancet."},{"issue":"4","key":"4787_CR2","doi-asserted-by":"publisher","first-page":"337","DOI":"10.1007\/s00586-004-0731-3","volume":"14","author":"EK Hansson","year":"2005","unstructured":"Hansson EK, Hansson TH. The costs for persons sick-listed more than one month because of low back or neck problems. A two-year prospective study of Swedish patients. Eur Spine J. 2005;14(4):337\u201345.","journal-title":"Eur Spine J"},{"issue":"13","key":"4787_CR3","doi-asserted-by":"publisher","first-page":"1050","DOI":"10.1097\/BRS.0b013e3181e70488","volume":"36","author":"LC Lambeek","year":"2011","unstructured":"Lambeek LC, van Tulder MW, Swinkels IC, Koppes LL, Anema JR, van Mechelen W. The trend in total cost of back pain in the Netherlands in the period 2002 to 2007. Spine (Phila Pa 1976). 2011;36(13):1050\u20138.","journal-title":"Spine (Phila Pa 1976)"},{"key":"4787_CR4","first-page":"421","volume-title":"Cost of back pain in some OECD countries. Neck And back pain: The Scientific Evidence of Causes, Diagnosis Treatment","author":"AI Norlund","year":"2000","unstructured":"Norlund AI, Waddel G, Nachemson AL, Jonsson E. Cost of back pain in some OECD countries. Neck And back pain: The Scientific Evidence of Causes, Diagnosis Treatment. Philadelphia: Lippincott Williams, Wilkins; 2000. p. 421\u20135."},{"issue":"10137","key":"4787_CR5","doi-asserted-by":"publisher","first-page":"2356","DOI":"10.1016\/S0140-6736(18)30480-X","volume":"391","author":"J Hartvigsen","year":"2018","unstructured":"Hartvigsen J, Hancock MJ, Kongsted A, Louw Q, Ferreira ML, Genevay S, et al. What low back pain is and why we need to pay attention. Lancet. 2018;391(10137):2356\u201367.","journal-title":"Lancet."},{"issue":"1","key":"4787_CR6","doi-asserted-by":"publisher","first-page":"3","DOI":"10.1186\/s12874-017-0467-5","volume":"18","author":"M Koitsalu","year":"2018","unstructured":"Koitsalu M, Eklund M, Adolfsson J, Gr\u00f6nberg H, Brandberg Y. Effects of pre-notification, invitation length, questionnaire length and reminder on participation rate: a quasi-randomised controlled trial. BMC Med Res Methodol. 2018;18(1):3.","journal-title":"BMC Med Res Methodol"},{"key":"4787_CR7","volume-title":"Principles of exposure measurement in epidemiology. Paperback ed","author":"BK Armstrong","year":"1995","unstructured":"Armstrong BK. In: White E, Saracci R, editors. Principles of exposure measurement in epidemiology. Paperback ed. Oxford: Oxford University Press; 1995."},{"issue":"6","key":"4787_CR8","doi-asserted-by":"publisher","first-page":"493","DOI":"10.1093\/aje\/kwj069","volume":"163","author":"LL Gluud","year":"2006","unstructured":"Gluud LL. Bias in clinical intervention research. Am J Epidemiol. 2006;163(6):493\u2013501.","journal-title":"Am J Epidemiol"},{"key":"4787_CR9","volume-title":"Modern epidemiology","author":"KGS Rothman","year":"2008","unstructured":"Rothman KGS, Lash TL. Modern epidemiology. 3rd ed. Philadelphia: Lippincott Williams & Wilkins; 2008.","edition":"3"},{"key":"4787_CR10","first-page":"Mr000008","volume":"3","author":"PJ Edwards","year":"2009","unstructured":"Edwards PJ, Roberts I, Clarke MJ, Diguiseppi C, Wentz R, Kwan I, et al. Methods to increase response to postal and electronic questionnaires. Cochrane Database Syst Rev. 2009;3:Mr000008.","journal-title":"Cochrane Database Syst Rev"},{"issue":"8","key":"4787_CR11","doi-asserted-by":"publisher","first-page":"e0202755","DOI":"10.1371\/journal.pone.0202755","volume":"13","author":"M Brtnikova","year":"2018","unstructured":"Brtnikova M, Crane LA, Allison MA, Hurley LP, Beaty BL, Kempe A. A method for achieving high response rates in national surveys of U.S. primary care physicians. PLoS One. 2018;13(8):e0202755.","journal-title":"PLoS One"},{"issue":"4","key":"4787_CR12","doi-asserted-by":"publisher","first-page":"276","DOI":"10.1111\/jphd.12054","volume":"74","author":"E Funkhouser","year":"2014","unstructured":"Funkhouser E, Fellows JL, Gordan VV, Rindal DB, Foy PJ, Gilbert GH. Supplementing online surveys with a mailed option to reduce bias and improve response rate: the National Dental Practice-Based Research Network. J Public Health Dent. 2014;74(4):276\u201382.","journal-title":"J Public Health Dent"},{"key":"4787_CR13","doi-asserted-by":"publisher","first-page":"62","DOI":"10.1186\/1471-2288-11-62","volume":"11","author":"S Sahlqvist","year":"2011","unstructured":"Sahlqvist S, Song Y, Bull F, Adams E, Preston J, Ogilvie D, et al. Effect of questionnaire length, personalisation and reminder type on response rate to a complex postal survey: randomised controlled trial. BMC Med Res Methodol. 2011;11:62.","journal-title":"BMC Med Res Methodol"},{"key":"4787_CR14","doi-asserted-by":"publisher","first-page":"167","DOI":"10.1093\/poq\/nfn011","volume":"72","author":"R Groves","year":"2008","unstructured":"Groves R, Peytcheva E. The impact of nonresponse rates on nonresponse Bias: a Meta-analysis. Public Opin Q. 2008;72:167\u201389.","journal-title":"Public Opin Q"},{"issue":"10","key":"4787_CR15","doi-asserted-by":"publisher","first-page":"1811","DOI":"10.2105\/AJPH.2008.154161","volume":"99","author":"S Lee","year":"2009","unstructured":"Lee S, Brown ER, Grant D, Belin TR, Brick JM. Exploring nonresponse bias in a health survey using neighborhood characteristics. Am J Public Health. 2009;99(10):1811\u20137.","journal-title":"Am J Public Health"},{"issue":"6","key":"4787_CR16","doi-asserted-by":"publisher","first-page":"558","DOI":"10.1093\/aje\/kwg003","volume":"157","author":"J Brogger","year":"2003","unstructured":"Brogger J, Bakke P, Eide GE, Gulsvik A. Contribution of follow-up of nonresponders to prevalence and risk estimates: a Norwegian respiratory health survey. Am J Epidemiol. 2003;157(6):558\u201366.","journal-title":"Am J Epidemiol"},{"key":"4787_CR17","doi-asserted-by":"publisher","first-page":"26","DOI":"10.1186\/1471-2288-10-26","volume":"10","author":"NM Mealing","year":"2010","unstructured":"Mealing NM, Banks E, Jorm LR, Steel DG, Clements MS, Rogers KD. Investigation of relative risk estimates from studies of the same population with contrasting response rates and designs. BMC Med Res Methodol. 2010;10:26.","journal-title":"BMC Med Res Methodol"},{"issue":"1","key":"4787_CR18","doi-asserted-by":"publisher","first-page":"3","DOI":"10.1186\/1475-9276-3-3","volume":"3","author":"AJ Sogaard","year":"2004","unstructured":"Sogaard AJ, Selmer R, Bjertness E, Thelle D. The Oslo health study: the impact of self-selection in a large, population-based survey. Int J Equity Health. 2004;3(1):3.","journal-title":"Int J Equity Health"},{"issue":"1","key":"4787_CR19","doi-asserted-by":"publisher","first-page":"156","DOI":"10.1093\/eurpub\/cku057","volume":"25","author":"AI Christensen","year":"2015","unstructured":"Christensen AI, Ekholm O, Kristensen PL, Larsen FB, Vinding AL, Glumer C, et al. The effect of multiple reminders on response patterns in a Danish health survey. Eur J Pub Health. 2015;25(1):156\u201361.","journal-title":"Eur J Pub Health"},{"issue":"12","key":"4787_CR20","doi-asserted-by":"publisher","first-page":"1495","DOI":"10.1016\/j.ijsu.2014.07.013","volume":"12","author":"E von Elm","year":"2014","unstructured":"von Elm E, Altman DG, Egger M, Pocock SJ, Gotzsche PC, Vandenbroucke JP. The strengthening the reporting of observational studies in epidemiology (STROBE) statement: guidelines for reporting observational studies. Int J Surg. 2014;12(12):1495\u20139.","journal-title":"Int J Surg"},{"issue":"1","key":"4787_CR21","doi-asserted-by":"publisher","first-page":"47","DOI":"10.1186\/s12891-020-3062-6","volume":"21","author":"A Riis","year":"2020","unstructured":"Riis A, Karran EL, Thomsen JL, J\u00f8rgensen A, Holst S, Rolving N. The association between believing staying active is beneficial and achieving a clinically relevant functional improvement after 52\u2009weeks: a prospective cohort study of patients with chronic low back pain in secondary care. BMC Musculoskelet Disord. 2020;21(1):47.","journal-title":"BMC Musculoskelet Disord"},{"issue":"2","key":"4787_CR22","doi-asserted-by":"publisher","first-page":"141","DOI":"10.1097\/00007632-198303000-00004","volume":"8","author":"M Roland","year":"1983","unstructured":"Roland M, Morris R. A study of the natural history of back pain. Part I: development of a reliable and sensitive measure of disability in low-back pain. Spine. 1983;8(2):141\u20134.","journal-title":"Spine."},{"issue":"2","key":"4787_CR23","doi-asserted-by":"publisher","first-page":"145","DOI":"10.1097\/00007632-198303000-00005","volume":"8","author":"M Roland","year":"1983","unstructured":"Roland M, Morris R. A study of the natural history of low-back pain. Part II: development of guidelines for trials of treatment in primary care. Spine. 1983;8(2):145\u201350.","journal-title":"Spine."},{"issue":"17","key":"4787_CR24","doi-asserted-by":"publisher","first-page":"1899","DOI":"10.1097\/00007632-199509000-00011","volume":"20","author":"DL Patrick","year":"1995","unstructured":"Patrick DL, Deyo RA, Atlas SJ, Singer DE, Chapin A, Keller RB. Assessing health-related quality of life in patients with sciatica. Spine. 1995;20(17):1899\u2013908 discussion 909.","journal-title":"Spine."},{"issue":"18","key":"4787_CR25","first-page":"1875","volume":"165","author":"HB Albert","year":"2003","unstructured":"Albert HB, Jensen AM, Dahl D, Rasmussen MN. Criteria validation of the Roland Morris questionnaire. A Danish translation of the international scale for the assessment of functional level in patients with low back pain and sciatica. Ugeskr Laeger. 2003;165(18):1875\u201380.","journal-title":"Ugeskr Laeger"},{"issue":"1","key":"4787_CR26","doi-asserted-by":"publisher","first-page":"90","DOI":"10.1097\/BRS.0b013e31815e3a10","volume":"33","author":"RW Ostelo","year":"2008","unstructured":"Ostelo RW, Deyo RA, Stratford P, Waddell G, Croft P, Von Korff M, et al. Interpreting change scores for pain and functional status in low back pain: towards international consensus regarding minimal important change. Spine. 2008;33(1):90\u20134.","journal-title":"Spine."},{"issue":"1","key":"4787_CR27","doi-asserted-by":"publisher","first-page":"45","DOI":"10.1016\/j.jclinepi.2005.03.018","volume":"59","author":"K Jordan","year":"2006","unstructured":"Jordan K, Dunn KM, Lewis M, Croft P. A minimal clinically important difference was derived for the Roland-Morris disability questionnaire for low back pain. J Clin Epidemiol. 2006;59(1):45\u201352.","journal-title":"J Clin Epidemiol"},{"issue":"5","key":"4787_CR28","doi-asserted-by":"publisher","first-page":"592","DOI":"10.1093\/fampra\/cmg517","volume":"20","author":"AM Elliott","year":"2003","unstructured":"Elliott AM, Hannaford PC. Third mailings in epidemiological studies: are they really necessary? Fam Pract. 2003;20(5):592\u20134.","journal-title":"Fam Pract"},{"issue":"9","key":"4787_CR29","doi-asserted-by":"publisher","first-page":"959","DOI":"10.1016\/j.jclinepi.2005.03.002","volume":"58","author":"M Wensing","year":"2005","unstructured":"Wensing M, Schattenberg G. Initial nonresponders had an increased response rate after repeated questionnaire mailings. J Clin Epidemiol. 2005;58(9):959\u201361.","journal-title":"J Clin Epidemiol"},{"issue":"5","key":"4787_CR30","doi-asserted-by":"publisher","first-page":"508","DOI":"10.1111\/j.1753-6405.2010.00598.x","volume":"34","author":"CL Breen","year":"2010","unstructured":"Breen CL, Shakeshaft AP, Doran CM, Sanson-Fisher RW, Mattick RP. Cost-effectiveness of follow-up contact for a postal survey: a randomised controlled trial. Aust N Z J Public Health. 2010;34(5):508\u201312.","journal-title":"Aust N Z J Public Health"},{"key":"4787_CR31","doi-asserted-by":"publisher","first-page":"104058","DOI":"10.1016\/j.ijnurstu.2021.104058","volume":"123","author":"DR Sammut","year":"2021","unstructured":"Sammut DR, Griscti DO, Norman PIJ. Strategies to improve response rates to web surveys: a literature review. Int J Nurs Stud. 2021;123:104058. https:\/\/doi.org\/10.1016\/j.ijnurstu.2021.104058.","journal-title":"Int J Nurs Stud"},{"issue":"1","key":"4787_CR32","doi-asserted-by":"publisher","first-page":"125","DOI":"10.1007\/s10805-009-9072-5","volume":"7","author":"J Schirmer","year":"2009","unstructured":"Schirmer J. Ethical issues in the use of multiple survey reminders. J Acad Ethics. 2009;7(1):125\u201339.","journal-title":"J Acad Ethics"},{"issue":"1","key":"4787_CR33","doi-asserted-by":"publisher","first-page":"90","DOI":"10.1016\/j.jclinepi.2011.04.011","volume":"65","author":"R Lall","year":"2012","unstructured":"Lall R, Mistry D, Bridle C, Lamb SE. Telephone interviews can be used to collect follow-up data subsequent to no response to postal questionnaires in clinical trials. J Clin Epidemiol. 2012;65(1):90\u20139.","journal-title":"J Clin Epidemiol"},{"key":"4787_CR34","doi-asserted-by":"publisher","first-page":"2331","DOI":"10.2147\/JPR.S139445","volume":"10","author":"P Campbell","year":"2017","unstructured":"Campbell P, Hope K, Dunn KM. The pain, depression, disability pathway in those with low back pain: a moderation analysis of health locus of control. J Pain Res. 2017;10:2331\u20139.","journal-title":"J Pain Res"},{"issue":"3","key":"4787_CR35","doi-asserted-by":"publisher","first-page":"313","DOI":"10.1016\/j.ejpain.2010.07.008","volume":"15","author":"KM Dunn","year":"2011","unstructured":"Dunn KM, Jordan KP, Croft PR. Contributions of prognostic factors for poor outcome in primary care low back pain patients. Eur J Pain. 2011;15(3):313\u20139.","journal-title":"Eur J Pain"},{"issue":"3","key":"4787_CR36","doi-asserted-by":"publisher","first-page":"e10672","DOI":"10.2196\/10672","volume":"21","author":"D Fitzgerald","year":"2019","unstructured":"Fitzgerald D, Hockey R, Jones M, Mishra G, Waller M, Dobson A. Use of Online or Paper Surveys by Australian Women: Longitudinal Study of Users, Devices, and Cohort Retention. J Med Internet Res. 2019;21(3):e10672\u2013e.","journal-title":"J Med Internet Res"},{"issue":"1","key":"4787_CR37","doi-asserted-by":"publisher","first-page":"84","DOI":"10.1080\/00222216.2014.11950314","volume":"46","author":"P Ward","year":"2014","unstructured":"Ward P, Clark T, Zabriskie R, Morris T. Paper\/pencil versus online data collection. J Leis Res. 2014;46(1):84\u2013105.","journal-title":"J Leis Res"},{"issue":"4","key":"4787_CR38","doi-asserted-by":"publisher","first-page":"419","DOI":"10.1111\/j.1524-4733.2008.00470.x","volume":"12","author":"SJ Coons","year":"2009","unstructured":"Coons SJ, Gwaltney CJ, Hays RD, Lundy JJ, Sloan JA, Revicki DA, et al. Recommendations on evidence needed to support measurement equivalence between electronic and paper-based patient-reported outcome (PRO) measures: ISPOR ePRO good research practices task force report. Value Health. 2009;12(4):419\u201329. https:\/\/doi.org\/10.1111\/j.1524-4733.2008.00470.x.","journal-title":"Value Health"},{"issue":"11","key":"4787_CR39","doi-asserted-by":"publisher","first-page":"2136","DOI":"10.1016\/j.arth.2014.07.003","volume":"29","author":"W Griffiths-Jones","year":"2014","unstructured":"Griffiths-Jones W, Norton MR, Fern ED, Williams DH. The equivalence of remote electronic and paper patient reported outcome (PRO) collection. J Arthroplast. 2014;29(11):2136\u20139. https:\/\/doi.org\/10.1016\/j.arth.2014.07.003.","journal-title":"J Arthroplast"},{"key":"4787_CR40","doi-asserted-by":"publisher","first-page":"b2393","DOI":"10.1136\/bmj.b2393","volume":"338","author":"JA Sterne","year":"2009","unstructured":"Sterne JA, White IR, Carlin JB, Spratt M, Royston P, Kenward MG, et al. Multiple imputation for missing data in epidemiological and clinical research: potential and pitfalls. BMJ. 2009;338:b2393. https:\/\/doi.org\/10.1136\/bmj.b2393.","journal-title":"BMJ."}],"container-title":["BMC Musculoskeletal Disorders"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/link.springer.com\/content\/pdf\/10.1186\/s12891-021-04787-4.pdf","content-type":"application\/pdf","content-version":"vor","intended-application":"text-mining"},{"URL":"https:\/\/link.springer.com\/article\/10.1186\/s12891-021-04787-4\/fulltext.html","content-type":"text\/html","content-version":"vor","intended-application":"text-mining"},{"URL":"https:\/\/link.springer.com\/content\/pdf\/10.1186\/s12891-021-04787-4.pdf","content-type":"application\/pdf","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2022,7,13]],"date-time":"2022-07-13T10:03:26Z","timestamp":1657706606000},"score":1,"resource":{"primary":{"URL":"https:\/\/bmcmusculoskeletdisord.biomedcentral.com\/articles\/10.1186\/s12891-021-04787-4"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2021,10,20]]},"references-count":40,"journal-issue":{"issue":"1","published-print":{"date-parts":[[2021,12]]}},"alternative-id":["4787"],"URL":"https:\/\/doi.org\/10.1186\/s12891-021-04787-4","relation":{},"ISSN":["1471-2474"],"issn-type":[{"value":"1471-2474","type":"electronic"}],"subject":[],"published":{"date-parts":[[2021,10,20]]},"assertion":[{"value":"13 April 2021","order":1,"name":"received","label":"Received","group":{"name":"ArticleHistory","label":"Article History"}},{"value":"12 October 2021","order":2,"name":"accepted","label":"Accepted","group":{"name":"ArticleHistory","label":"Article History"}},{"value":"20 October 2021","order":3,"name":"first_online","label":"First Online","group":{"name":"ArticleHistory","label":"Article History"}},{"order":1,"name":"Ethics","group":{"name":"EthicsHeading","label":"Declarations"}},{"value":"All patients gave written informed consent online and were informed that their consent could be withdrawn at any time. This is an observational study, and all patients received treatment as usual. In accordance with the Danish Scientific Ethical Committees Act, survey studies do not require approval by an ethics committee (\u00a714, part 2) []. All experimental protocols were approved by the executive management of the Spine Centre at Silkeborg Regional Hospital. The original trial is registered with the Danish Data Protection Agency (Central Denmark Region, journal no. 1\u201316\u201302-23-17).","order":2,"name":"Ethics","group":{"name":"EthicsHeading","label":"Ethics approval and consent to participate"}},{"value":"Not applicable.","order":3,"name":"Ethics","group":{"name":"EthicsHeading","label":"Consent for publication"}},{"value":"AR is member of the editorial board at BMC Musculoskeletal Disorders. The other authors declare that they have no competing interests.","order":4,"name":"Ethics","group":{"name":"EthicsHeading","label":"Competing interests"}}],"article-number":"893"}}