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These are our questionnaires for measuring symptoms of ME/CFS, ME, and COVID-19. Psychometric properties of our surveys are cited below. All instruments are free to use. If you are considering translating any of our surveys, please let us know as we would be happy to provide you with helpful suggestions.


DePaul Symptom Questionnaire-1 (DSQ-1):

DSQ-1 English Version – PDF


Jason, et al. (2010). The Development of a Revised Canadian Myalgic Encephalomyelitis Chronic Fatigue Syndrome Case Definition

Jason & Sunnquist (2018). The Development of the DePaul Symptom Questionnaire


Case Definition SPSS Scoring Syntax

Case Definition R Scoring Syntax

REDCap Instrument


  1. Dutch Version 
  2. Japanese Version
  3. Norwegian Version
  4. Spanish Version
  5. Brazilian Portuguese Version

DePaul Symptom Questionnaire-2 (DSQ-2):

DSQ-2 English Version – PDF


Bedree, Sunnquist, & Jason (2019). The DePaul Symptom Questionnaire-2: A Validation Study


Case Definition SPSS Scoring Syntax

REDCap Instrument


  1. Polish Version
  2. German Version

DePaul Symptom Questionnaire – Short Form (DSQ-SF):

DSQ-SF English Version – PDF


Sunnquist, Lazarus, & Jason (2019). The Development of a Short Form of the DePaul Symptom Questionnaire


Case Definition SPSS Scoring Syntax

REDCap Instrument


  1. Finnish Version
  2. Spanish Version
  3. German Version

DePaul Symptom Questionnaire – Brief (DSQ-Brief):

DSQ-Brief – MSWord Document

Pediatric Questionnaires

DePaul Symptom Questionnaire – Pediatric Screening Questionnaire (DSQ-PSQ):

Pediatric Screening Questionnaire (DSQ-PSQ)

Now available in REDCap instrument library (requires login -> search: “DSQ-Pediatric”)

DePaul Symptom Questionnaire – Pediatric (DSQ-PED):

DSQ-PED (Parent Form)

DSQ-PED (Child Form)


Jason, et al. (2020). The Prevalence of Pediatric Myalgic Encephalomyelitis/ Chronic Fatigue Syndrome in a Community‑Based Sample


DSQ-PSQ SPSS Scoring Syntax


  1. Parent Form – Latvian Version
  2. Child Form – Latvian Version

Post-Exertional Malaise:

DePaul Symptom Questionnaire – Post-Exertional Malaise (DSQ-PEM):

DSQ-PEM English Version – PDF & Scoring Guide


Cotler et al. (2018). A Brief Questionnaire to Assess Post-Exertional Malaise


  1. French Version – DSQ-PEM
  2. German Version – DSQ-PEM

DePaul Post-Exertional Malaise Questionnaire (DPEMQ):



Jason, et al. (2018). The development of an instrument to assess post-exertional malaise in patients with myalgic encephalomyelitis and chronic fatigue syndrome

DePaul Symptom Questionnaire – COVID (DSQ-COVID):



  1. German Version
  2. Brazilian Portuguese Version

Other Instruments:

Fennell Scale 

The Chronic Fatigue Syndrome Attitudes Test Questions 



Nepotchatykh, E., Caraus, I., Elremaly, W., Leveau, C., Elbakry, M., Godbout, C., Rostami-Afshari, B., Petre, D., Khatami, N., Franco, A., & Moreau, A. (2023). Circulating microRNA expression signatures accurately discriminate myalgic encephalomyelitis from fibromyalgia and comorbid conditions. Scientific Reports, 13, 1896. https://doi.org/10.1038/s41598-023-28955-9

Che, X., Brydges, C. R., Yu, Y., Price, A., Joshi, S., Roy, A., Lee, B., Barupal, D. K., Cheng, A., Palmer, D. M., Levine, S., Peterson, D. L., Vernon, S. D., Bateman, L., Hornig, M., Montoya, J. G., Komaroff, A. L., Fiehn, O., & Lipkin, W. I. (2022). Evidence for Peroxisomal Dysfunction and Dysregulation of the CDP-Choline Pathway in Myalgic Encephalomyelitis/Chronic Fatigue Syndrome. medRxiv, 2021.06.14.21258895. https://doi.org/10.1101/2021.06.14.21258895

Klaver-Krol, E.G., Hermens, H.J., Vermeulen, R.C., Klaver, M.M., Luyten, H., Henriquez, N.R., & Zwarts, M.J. (2021). Chronic fatigue syndrome: Abnormally fast muscle fiber conduction in the membranes of motor units at low static force load. Clinical Neurophysiology,132(4), 967-974. https://doi.org/10.1016/j.clinph.2020.11.043.

Conroy, K., Bhatia, S., Islam, M., & Jason, L.A. (2021). Homebound versus bedridden status among patients with Myalgic Encephalomyelitis/Chronic Fatigue Syndrome. Healthcare, 9(2), 106. PMCID: PMC7909520 https://doi.org/10.3390/healthcare9020106

Nepotchatykh, E., Elremaly, W., Caraus, I., Godbout, C., Leveau, C., Chalder L., Beaudin, C., Kanamaru, E., Kosovskaia, R., Lauzon, S., Maillet, Y, Franco, A., Lascau-Coman, V., Bouhanik, S., Gaitan, Y. P., Li, D., & Moreau, A. (2020) Profile of circulating microRNAs in myalgic encephalomyelitis and their relation to symptom severity, and disease pathophysiology. Sci Rep. 10:19620. https://doi.org/10.1038/s41598-020-76438-y

Lande, A. (2021). Human leukocyte antigen associations in myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS) and immune modulating treatment. [Doctoral dissertation, University of Oslo] https://www.duo.uio.no/bitstream/handle/10852/86195/PhD-Lande-2021.pdf 

Lande, A., Fluge, Ø., Strand, E.B., Flåm, S. T., Sosa, D. D., Mella, O., Egeland, T., Saugstad, O. D., Lie, B. A., & Viken, M. K. (2020). Human Leukocyte Antigen alleles associated with Myalgic Encephalomyelitis/Chronic Fatigue Syndrome (ME/CFS). Sci Rep, 10(5267). https://doi.org/10.1038/s41598-020-62157-x

Kemp, J., Sunnquist, M., Jason, L.A., & Newton, J.L.  (2019). Autonomic dysfunction in myalgic encephalomyelitis and chronic fatigue syndrome: Comparing self-report and objective measures. Clinical Autonomic Research, 29(4), 475-477. PMCID: PMC6697554  https://doi.org/10.1007/s10286-019-00615-x 

Huber, K., Sunnquist, M., & Jason, L.A. (2018). Latent class analysis of a heterogeneous international sample of patients with myalgic encephalomyelitis/chronic fatigue syndrome. Fatigue: Biomedicine, Health & Behavior, (6)3, 163-178. PMCID: PMC6703845 https://doi.org/10.1080/21641846.2018.1494530

Strand, E.B., Lillestøl, K., Jason, L.A., Tveito, K., Diep, L. M. Valla, S.S., Sunnquist, M., Helland, I.B., Herder, I., & Dammen, T. (2016): Comparing the DePaul Symptom Questionnaire with physician assessments: A preliminary study, Fatigue: Biomedicine, Health & Behavior4(1), 52-62. https://doi.org/10.1080/21641846.2015.1126026

Murdock KW, Wang XS, Shi Q, Cleeland CS, Fagundes CP, Vernon SD.(2016) The utility of patient-reported outcome measures among patients with myalgic encephalomyelitis/chronic fatigue syndrome. Qual Life Res, 26, 913–21. doi: 10.1007/s11136-016-1406-3

Jason, L.A., Kot, B., Sunnquist, M., Brown, A., Evans, M., Jantke, R., Williams, Y., Furst, J., & Vernon, S.D. (2015). Chronic fatigue Syndrome and myalgic encephalomyelitis: Toward an empirical case definition. Health Psychology and Behavioral Medicine: An Open Access Journal, 3, 82-93. PMCID: PMC4443921 https://doi.org/10.1080/21642850.2015.1014489

Jason, L.A., Kot, B., Sunnquist, M., Brown, A., Reed, J., Furst, J., Newton, J. L., Strand, E.B., & Vernon, S. D. (2015). Comparing and contrasting consensus versus empirical domains. Fatigue: Biomedicine, Health & Behavior, 3, 63-74. PMCID: PMC4788637 http://doi.org/10.1080/21641846.2015.1017344

Jason, L.A., Sunnquist, M., Brown, A., Newton, J. L., Strand, E. B., & Vernon, S. D. (2015). Chronic fatigue syndrome versus Systemic Exertion Intolerance Disease.Fatigue: Biomedicine, Health & Behavior, 3, 127–141. PMCID:PMC4556426 https://doi.org/10.1080/21641846.2015.1051291

Jason, L.A., So, S., Brown, A.A., Sunnquist, M., & Evans, M. (2015). Test-retest reliability of the DePaul Symptom Questionnaire. Fatigue: Biomedicine, Health & Behavior, 3(1), 16-32. PMCID: PMC4788471 http://doi.org/10.1080/21641846.2014.978110

Jason, L.A., Sunnquist, M., Brown, A., Evans, M., Vernon, S.D., Furst, J., & Simonis, V. (2014). Examining case definition criteria for chronic fatigue syndrome and Myalgic Encephalomyelitis. Fatigue: Biomedicine, Health, and Behavior, 2, 40-56. PMCID: PMC3912876 https://doi.org/10.1080/21641846.2013.862993

Hutchinson, C.V., Maltby, J., Badham, S.P., & Jason, L.A. (2014). Vision-related symptoms as a clinical feature of Chronic Fatigue Syndrome/Myalgic Encephalomyelitis? Evidence from the DePaul Symptom Questionnaire. British Journal of Ophthalmology, 98, 144-145. https://doi.org/10.1136/bjophthalmol-2013-304439

Brown, A.A., & Jason, L.A. (2014). Validating a measure of myalgic encephalomyelitis/chronic fatigue syndrome symptomatology. Fatigue: Biomedicine, Health & Behavior, 2, 132–152. PMCID: PMC4871625 https://doi.org/10.1080/21641846.2014.928014

Jason, L.A., Brown, A., Evans, M., Sunnquist, M., & Newton, J.L. (2013). Contrasting Chronic Fatigue Syndrome versus Myalgic Encephalomyelitis/Chronic Fatigue Syndrome. Fatigue: Biomedicine, Health & Behavior, 1, 168–183.  PMCID: PMC3728084 https://doi.org/10.1080/21641846.2013.774556

Jason, L.A., Evans, M., Porter, N., Brown, M., Brown, A., Hunnell, J., Anderson, V., Lerch, A., De Meirleir, K., & Friedberg, F. (2010). The development of a revised Canadian Myalgic Encephalomyelitis-Chronic Fatigue Syndrome case definition. American Journal of Biochemistry and Biotechnology, 6(2), 120-135. https://doi.org/10.3844/ajbbsp.2010.120.135



Cornelissen, M.E.B., Bloemsma, L.D., Baalbaki, N., et al. (2023). Fatigue in post COVID-19 patients: the P4O2 COVID-19 study. European Respiratory Journal, 62 (suppl 67) PA4574; DOI: 10.1183/13993003.congress-2023.PA4574

Van Eeden, C., Mohazab, N., Redmond, D., Yacyshyn, E., Clifford. A., Russell, A. S., Osman, M. S., & Cohen Tervaert, J. W. (2023). Myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS) and fibromyalgia: PR3-versus MPO-ANCA-associated vasculitis, an exploratory cross-sectional study. The Lancet Regional Health – Americas. 20. https://doi.org/10.1016/j.lana.2023.100460

Brod, M., McLeod, L., Markova, D., Gianettoni, J., Mourya, S., Lin, Z., Shu, A., & Smith, A. (2021). Psychometric validation of the Hypoparathyroidism Patient Experience Scales (HPES). Journal of Patient-Reported Outcomes, 5(70). https://doi.org/10.1186/s41687-021-00320-2

Bedree, H., Sunnquist, M., & Jason, L.A. (2019). The DePaul Symptom Questionnaire-2: A validation study. Fatigue: Biomedicine, Health & Behavior, 7(3), 166-179. PMCID: PMC7367506 https://doi.org/10.1080/21641846.2019.1653471

Jason, L.A., Ohanian, D., Brown, A., Sunnquist, M., McManimen, S., Klebek, L., Fox, P., & Sorenson, M. (2017). Differentiating Multiple Sclerosis from Myalgic Encephalomyelitis and Chronic Fatigue Syndrome. Insights in Biomedicine, 2:11. PMCID: PMC5800741 https://doi.org/10.21767/2572-5610.100011

Ohanian, D., Brown, A., Sunnquist, M., Furst, J., Nicholson, N., Klebek, L., & Jason, L.A. (2016). Identifying key symptoms differentiating Myalgic Encephalomyelitis and Chronic Fatigue Syndrome from Multiple Sclerosis. EC Neurology, 4, 41-45.


DSQ-SF (Short-Form)

Shaheen, N., & Shaheen, A. (2022). Study Protocol Clinical Trial Medicine ® Long-term sequelae of COVID-19 (myalgic encephalomyelitis) An international cross-sectional study. Medicine, 101: e31819. 10.1097/MD.0000000000031819.

Rekeland IG, Sørland K, Bruland O, Risa K, Alme K, Dahl O, et al. (2022) Activity monitoring and patient-reported outcome measures in Myalgic Encephalomyelitis/Chronic Fatigue Syndrome patients. PLoS ONE 17(9): e0274472. https://doi.org/10.1371/journal.pone.0274472

Jimeno‑Almazán, A., Martínez‑Cava, A.,  Buendía‑Romero, A., Franco‑López, F., Sánchez‑Agar, J.A., Sánchez‑Alcaraz, B.J., Tufano, J.J., Pallarés, J.G., & Courel‑Ibáñez, J. (2022). Relationship between the severity of persistent symptoms, physical fitness, and cardiopulmonary function in post‑COVID‑19 condition. A population‑based analysis. Internal and Emergency Medicine. https://doi.org/10.1007/s11739-022-03039-0

Froehlich, L., Hattesohl, D.B.R., Cotler, J., Jason, L.A., Scheibenbogen, C., & Behrends, U.  (2021b). Causal attributions and perceived stigma for Myalgic Encephalomyelitis/ Chronic Fatigue Syndrome. Journal of Health Psychology. Published online July 9, 2021. https://doi.org/10.1177/13591053211027631

Froehlich, L., Hattesohl, D. B. R., Jason, L. A., Scheibenbogen, C., Behrends, U., & Thoma, M. (2021). Medical care situation of people with Myalgic Encephalomyelitis/Chronic fatigue syndrome in Germany. Medicina, 57(7), 646. https://doi.org/10.3390/medicina57070646

Sunnquist, M., Lazarus, S., & Jason, L. A. (2019). The development of a short form of the DePaul Symptom Questionnaire. Rehabilitation Psychology, 64(4), 453–462. https://doi.org/10.1037/rep0000285



RECOVER-VITAL: A Platform Protocol for Evaluation of Interventions for Viral Persistence, Viral Reactivation, and Immune Dysregulation in Post-Acute Sequelae of SARS-CoV-2 Infection (PASC)  [PDF] RECOVER-VITAL: A Platform Protocol for Evaluation of Interventions for Viral Persistence, Viral Reactivation, and Immune Dysregulation in Post-Acute …

Paffrath, A. Kim, L., Kedor, C., Stein, E., Rust, R., Freitag, H., Hoppmann, U., Hanitsch, L.G., Bellmann-Strobl, J., Wittke, K., Scheibenbogen, C.,  Sotzny, F. (2024). Repeated Hand Grip Strength is an Objective Marker for Disability and Severity of Key Symptoms in Post-COVID ME/CFS. medRxiv. https://doi.org/10.1101/2024.01.25.24301776

Appelman, B., Charlton, B. T., Goulding, R. P., Kerkhoff, T. J., Breedveld, E. A., Noort, W., Offringa, C., Bloemers, F. W., van Weeghel, M., Schomakers, B. V., Coelho, P., Posthuma, J. J., Aronica, E., Joost Wiersinga, W., van Vugt, M., & Wüst, R. C. I. (2024). Muscle abnormalities worsen after post-exertional malaise in long COVID. Nature communications15(1), 17. https://doi.org/10.1038/s41467-023-44432-3

Wernhart S, Weihe E, Totzeck M, Balcer B, Rassaf T, Luedike P. (2023) Cardiopulmonary Profiling of Athletes with Post-Exertional Malaise after COVID-19 Infection—A Single-Center Experience. Journal of Clinical Medicine. 12, 13, 4348. https://doi.org/10.3390/jcm12134348

Pagen, D. M. E., Van Herck, M., van Bilsen, C. J. A., Brinkhues, S., Konings, K., den Heijer, C. D. J., Spruit, M. A., Hoebe, C. J. P. A., & Dukers-Muijrers, N. H. T. M. (2023). High proportions of post-exertional malaise and orthostatic intolerance in people living with post-COVID-19 condition: the PRIME post-COVID study. Frontiers in medicine10, 1292446. PMCID: PMC10757844. https://doi.org/10.3389/fmed.2023.1292446

Tanguay, P., Gaboury, I., Daigle, F., Bhéreur, A., Dubois, O., Lagueux, E., Naye, F., Tousignant, M., Marquis N., &  Décary, S. (2023) Post-exertional malaise may persist in Long COVID despite learning STOP-REST-PACE, Fatigue: Biomedicine, Health & Behavior, 11:2-4, 113-128, DOI: 10.1080/21641846.2023.2222199

Rathgeb, C., Pawellek, M., Behrends, U., Alberer, M., Kabesch, M., Gerling, S., Brandstetter, S., & Apfelbacher, C. (2023). The Evaluation of Health Care Services for Children and Adolescents With Post-COVID-19 Condition: Protocol for a Prospective Longitudinal Study. JMIR Research Protocols12, e41010. https://doi.org/10.2196/41010

Gattoni, C., Abbasi, A., Ferguson, C., Heffernan, C., Dinnen, E., Heutlinger, O., Nguyen, L., Lanks, C.W., Decato, T.W., Casaburi, R., Rossiter, H.B., Stringer, W.W. (2023). Is a Two-Day Cardiopulmonary Exercise Test a Valid Tool for The Diagnosis of Post-Exertional Malaise in Long COVID?, International Journal of Exercise Science: Conference Proceedings,14(3), 135. https://digitalcommons.wku.edu/ijesab/vol14/iss3/135

Nepotchatykh, E., Caraus, I., Elremaly, W. et al. Circulating microRNA expression signatures accurately discriminate myalgic encephalomyelitis from fibromyalgia and comorbid conditions. Sci Rep 13, 1896 (2023). https://doi.org/10.1038/s41598-023-28955-9

Klein, J., Wood, J., Jaycox, J. R., Dhodapkar, R. M., Lu, P., Gehlhausen, J. R., Tabachnikova, A., Greene, K., Tabacof, L., Malik, A. A., Silva Monteiro, V., Silva, J., Kamath, K., Zhang, M., Dhal, A., Ott, I. M., Valle, G., Peña-Hernández, M., Mao, T., Bhattacharjee, B., … Iwasaki, A. (2023). Distinguishing features of long COVID identified through immune profiling. Nature623(7985), 139–148. https://doi.org/10.1038/s41586-023-06651-y

Taenzer, M., Löffler-Ragg, J., Schroll, A., Monfort-Lanzas, P., Engl, S., Weiss, G., Brigo, N., & Kurz, K. (2023). Urine Metabolite Analysis to Identify Pathomechanisms of Long COVID: A Pilot Study. International journal of tryptophan research: IJTR16, 11786469231220781. https://doi.org/10.1177/11786469231220781

Twomey, R., DeMars, J., Franklin, K., Culos-Reed, S.N., Weatherald, J., & Wrightson, J.G. (2022). Chronic Fatigue and Postexertional Malaise in People Living With Long COVID: An Observational Study, Physical Therapy, 102, 4, pzac005, https://doi.org/10.1093/ptj/pzac005

Haffke, M., Freitag, H., Rudolf, G. et al. (2022). Endothelial dysfunction and altered endothelial biomarkers in patients with post-COVID-19 syndrome and chronic fatigue syndrome (ME/CFS). J Transl Med, 20, 138. https://doi.org/10.1186/s12967-022-03346-2

Twomey, R., Yeung, S. T., Wrightson, J.G., Millet, G.Y., S.  Culos-Reed,N. (2020). Post-exertional Malaise in People with Chronic Cancer-Related Fatigue, Journal of Pain and Symptom Management, Volume 60, Issue 2, 407-416, https://doi.org/10.1016/j.jpainsymman.2020.02.012.

Cotler, J., Katz, B. Z., Reurts-Post, C., Vermeulen, R., & Jason, L. A. (2020). A hierarchical logistic regression predicting rapid respiratory rates from post-exertional malaise. Fatigue: Biomedicine, Health & Behavior. https://doi.org/10.1080/21641846.2020.1845287

Holtzman, C.S., Fisher, C., Bhatia, S., & Jason, L.A. (2020). Factors affecting the characterization of post-exertional malaise derived from patient input. Journal of Health Disparities Research and Practice, 13(2), 51-64.

Holtzman, C.S., Bhatia, S., Cotler, J., & Jason, L.A. (2019). Assessment of post-exertional malaise (PEM) in patients with Myalgic Encephalomyelitis (ME) and Chronic Fatigue Syndrome (CFS): A patient-driven survey. Diagnostics, 9(1), 26. PMCID: PMC6468435 https://doi.org/10.3390/diagnostics9010026

McManimen, S. L., Sunnquist, M. L., & Jason, L. A. (2019). Deconstructing post-exertional malaise: An exploratory factor analysis. Journal of Health Psychology, 24(2), 188–198. PMCID: PMC5325824 https://doi.org/10.1177/1359105316664139

Jason, L.A., McManimen, S., Sunnquist, M., & Holtzman, C. (2018). Patient perceptions of post exertional malaise. Fatigue: Biomedicine, Health & Behavior, 6, 92-105. https://doi.org/10.1080/21641846.2018.1453265

Cotler, J., Holtzman, C., Dudun, C., & Jason, L.A. (2018). A brief questionnaire to assess post-exertional malaise. Diagnostics, 8, 66. https://doi.org/10.3390/diagnostics8030066


Leonard A. Jason, Sage Benner, Jacob Furst & Paul Cathey (2023) Developing and validating a brief screening scale for ME/CFS, Fatigue: Biomedicine, Health & Behavior, DOI: 10.1080/21641846.2023.2252613


Sorg, A. L., Becht, S., Marietta, J., Armann, J., Both, U. V., Hufnagel, M., Lander, F., Liese, J. G., Niehues, T., Verjans, E., Wetzke, M., Stojanov, S., Behrends, U., Drosten, C., Schroten, H., & Kries, R. V. (2022). Association of SARS-CoV-2 Seropositivity with ME/CFS among children and adolescents in Germany. JAMA Network Open 5(9). doi:10.1001/jamanetworkopen.2022.33454

Ekberg, K., Torres, C., & Jason, L.A. (in press). Parent-child discrepancies in health-related quality of life of children and adolescents with Myalgic Encephalomyelitis/Chronic Fatigue Syndrome. Quality of Life Research. Published online June 30, 2021. https://doi.org/10.1007/s11136-021-02919-w

Jason, L.A., Katz, B.Z., Sunnquist, M., Torres, C., Cotler, J., & Bhatia, S. (2020). The prevalence of pediatric myalgic encephalomyelitis/chronic fatigue syndrome in a community-based sample. Child & Youth Care Forum, 49(4), 563-579. PMCID: PMC8186295  https://doi.org/10.1007/s10566-019-09543-3

Schultz, K.R., Katz, B.Z., Bockian, N.R., & Jason, L.A. (2019). Relationships between autonomic and orthostatic self-report and physician ratings of orthostatic intolerance in youth. Clinical Therapeutics, 41, 633-640. PMCID: PMC6478562 https://doi.org/10.1016/j.clinthera.2019.02.010

Jason LA, Katz BZ, Mears C, Jantke R, Brown A, Sunnquist M, O’Connor K. (2015). Issues in estimating rates of pediatric chronic fatigue syndrome and myalgic encephalomyelitis in a community-based sample. Avicenna J Neuropsychophysiol, 2(4):e37281. doi: 10.17795/ajnpp-37281

Jason, L.A., Porter, N., Shelleby, E.,Till, L., Bell, D.S., Lapp, C.W., Rowe, K., & DeMeirleir, K. (2010). Examining criteria to diagnose ME/CFS in pediatric samples. Journal of Behavioral Health & Medicine, 1(3), 186-195. https://doi.org/10.1037/h0100551

Jason, L.A., Porter, N., Shelleby, E., Till, L., Bell, D.S., Lapp, C.W., Rowe, K., & De Meirleir, K. (2009). Severe versus moderate criteria for the new pediatric case definition for ME/CFS. Child Psychiatry and Human Development, 40, 609–620. PMID: 19513826 https://doi.org/10.1007/s10578-009-0147-8