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Journal of Neurology, Neurosurgery, and Psychiatry logoLink to Journal of Neurology, Neurosurgery, and Psychiatry
. 2002 Aug;73(2):116–120. doi: 10.1136/jnnp.73.2.116

Clinically important change in quality of life in epilepsy

S Wiebe 1, S Matijevic 1, M Eliasziw 1, P Derry 1
PMCID: PMC1737966  PMID: 12122166

Abstract

Background: Health related quality of life (HRQOL) is increasingly recognised as an important outcome in epilepsy. However, interpretation of HRQOL data is difficult because there is no agreement on what constitutes a clinically important change in the scores of the various instruments.

Objectives: To determine the minimum clinically important change, and small, medium, and large changes, in broadly used epilepsy specific and generic HRQOL instruments.

Methods: Patients with difficult to control focal epilepsy (n = 136) completed the QOLIE-89, QOLIE-31, SF-36, and HUI-III questionnaires twice, six months apart. Patient centred estimates of minimum important change, and of small, medium, and large change, were assessed on self administered 15 point global rating scales. Using regression analysis, the change in each HRQOL instrument that corresponded to the various categories of change determined by patients was obtained. The results were validated in a subgroup of patients tested at baseline and at nine months.

Results: The minimum important change was 10.1 for QOLIE-89, 11.8 for QOLIE-31, 4.6 for SF-36 MCS, 3.0 for SF-36 physical composite score, and 0.15 for HUI-III. All instruments differentiated between no change and minimum important change with precision, and QOLIE-89 and QOLIE-31 also distinguished accurately between minimum important change and medium or large change. Baseline HRQOL scores and the type of treatment (surgical or medical) had no impact on any of the estimates, and the results were replicated in the validation sample.

Conclusions: These estimates of minimum important change, and small, medium, and large changes, in four HRQOL instruments in patients with epilepsy are robust and can distinguish accurately among different levels of change. The estimates allow for categorisation of patients into various levels of change in HRQOL, and will be of use in assessing the effect of interventions in individual patients.

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Selected References

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  1. Baker D. W., Hays R. D., Brook R. H. Understanding changes in health status. Is the floor phenomenon merely the last step of the staircase? Med Care. 1997 Jan;35(1):1–15. doi: 10.1097/00005650-199701000-00001. [DOI] [PubMed] [Google Scholar]
  2. Bessette L., Sangha O., Kuntz K. M., Keller R. B., Lew R. A., Fossel A. H., Katz J. N. Comparative responsiveness of generic versus disease-specific and weighted versus unweighted health status measures in carpal tunnel syndrome. Med Care. 1998 Apr;36(4):491–502. doi: 10.1097/00005650-199804000-00005. [DOI] [PubMed] [Google Scholar]
  3. Birbeck G. L., Kim S., Hays R. D., Vickrey B. G. Quality of life measures in epilepsy: how well can they detect change over time? Neurology. 2000 May 9;54(9):1822–1827. doi: 10.1212/wnl.54.9.1822. [DOI] [PubMed] [Google Scholar]
  4. Bland J. M., Altman D. G. Comparing methods of measurement: why plotting difference against standard method is misleading. Lancet. 1995 Oct 21;346(8982):1085–1087. doi: 10.1016/s0140-6736(95)91748-9. [DOI] [PubMed] [Google Scholar]
  5. Cramer J. A., Perrine K., Devinsky O., Bryant-Comstock L., Meador K., Hermann B. Development and cross-cultural translations of a 31-item quality of life in epilepsy inventory. Epilepsia. 1998 Jan;39(1):81–88. doi: 10.1111/j.1528-1157.1998.tb01278.x. [DOI] [PubMed] [Google Scholar]
  6. Devinsky O., Vickrey B. G., Cramer J., Perrine K., Hermann B., Meador K., Hays R. D. Development of the quality of life in epilepsy inventory. Epilepsia. 1995 Nov;36(11):1089–1104. doi: 10.1111/j.1528-1157.1995.tb00467.x. [DOI] [PubMed] [Google Scholar]
  7. Dougherty C. M., Dewhurst T., Nichol W. P., Spertus J. Comparison of three quality of life instruments in stable angina pectoris: Seattle Angina Questionnaire, Short Form Health Survey (SF-36), and Quality of Life Index-Cardiac Version III. J Clin Epidemiol. 1998 Jul;51(7):569–575. doi: 10.1016/s0895-4356(98)00028-6. [DOI] [PubMed] [Google Scholar]
  8. Fischer D., Stewart A. L., Bloch D. A., Lorig K., Laurent D., Holman H. Capturing the patient's view of change as a clinical outcome measure. JAMA. 1999 Sep 22;282(12):1157–1162. doi: 10.1001/jama.282.12.1157. [DOI] [PubMed] [Google Scholar]
  9. Gliklich R. E., Hilinski J. M. Longitudinal sensitivity of generic and specific health measures in chronic sinusitis. Qual Life Res. 1995 Feb;4(1):27–32. doi: 10.1007/BF00434380. [DOI] [PubMed] [Google Scholar]
  10. Guyatt G. H., Cook D. J. Health status, quality of life, and the individual. JAMA. 1994 Aug 24;272(8):630–631. [PubMed] [Google Scholar]
  11. Guyatt G. H., Juniper E. F., Walter S. D., Griffith L. E., Goldstein R. S. Interpreting treatment effects in randomised trials. BMJ. 1998 Feb 28;316(7132):690–693. doi: 10.1136/bmj.316.7132.690. [DOI] [PMC free article] [PubMed] [Google Scholar]
  12. Jaeschke R., Singer J., Guyatt G. H. Measurement of health status. Ascertaining the minimal clinically important difference. Control Clin Trials. 1989 Dec;10(4):407–415. doi: 10.1016/0197-2456(89)90005-6. [DOI] [PubMed] [Google Scholar]
  13. Juniper E. F., Guyatt G. H., Willan A., Griffith L. E. Determining a minimal important change in a disease-specific Quality of Life Questionnaire. J Clin Epidemiol. 1994 Jan;47(1):81–87. doi: 10.1016/0895-4356(94)90036-1. [DOI] [PubMed] [Google Scholar]
  14. Lydick E., Epstein R. S. Interpretation of quality of life changes. Qual Life Res. 1993 Jun;2(3):221–226. doi: 10.1007/BF00435226. [DOI] [PubMed] [Google Scholar]
  15. McHorney C. A., Tarlov A. R. Individual-patient monitoring in clinical practice: are available health status surveys adequate? Qual Life Res. 1995 Aug;4(4):293–307. doi: 10.1007/BF01593882. [DOI] [PubMed] [Google Scholar]
  16. McHorney C. A., Ware J. E., Jr, Lu J. F., Sherbourne C. D. The MOS 36-item Short-Form Health Survey (SF-36): III. Tests of data quality, scaling assumptions, and reliability across diverse patient groups. Med Care. 1994 Jan;32(1):40–66. doi: 10.1097/00005650-199401000-00004. [DOI] [PubMed] [Google Scholar]
  17. Redelmeier D. A., Guyatt G. H., Goldstein R. S. Assessing the minimal important difference in symptoms: a comparison of two techniques. J Clin Epidemiol. 1996 Nov;49(11):1215–1219. doi: 10.1016/s0895-4356(96)00206-5. [DOI] [PubMed] [Google Scholar]
  18. Redelmeier D. A., Lorig K. Assessing the clinical importance of symptomatic improvements. An illustration in rheumatology. Arch Intern Med. 1993 Jun 14;153(11):1337–1342. [PubMed] [Google Scholar]
  19. Riddle D. L., Stratford P. W., Binkley J. M. Sensitivity to change of the Roland-Morris Back Pain Questionnaire: part 2. Phys Ther. 1998 Nov;78(11):1197–1207. doi: 10.1093/ptj/78.11.1197. [DOI] [PubMed] [Google Scholar]
  20. Samsa G., Edelman D., Rothman M. L., Williams G. R., Lipscomb J., Matchar D. Determining clinically important differences in health status measures: a general approach with illustration to the Health Utilities Index Mark II. Pharmacoeconomics. 1999 Feb;15(2):141–155. doi: 10.2165/00019053-199915020-00003. [DOI] [PubMed] [Google Scholar]
  21. Stewart A. L., Greenfield S., Hays R. D., Wells K., Rogers W. H., Berry S. D., McGlynn E. A., Ware J. E., Jr Functional status and well-being of patients with chronic conditions. Results from the Medical Outcomes Study. JAMA. 1989 Aug 18;262(7):907–913. [PubMed] [Google Scholar]
  22. Stratford P. W., Binkley J. M., Riddle D. L., Guyatt G. H. Sensitivity to change of the Roland-Morris Back Pain Questionnaire: part 1. Phys Ther. 1998 Nov;78(11):1186–1196. doi: 10.1093/ptj/78.11.1186. [DOI] [PubMed] [Google Scholar]
  23. Torrance G. W., Feeny D. H., Furlong W. J., Barr R. D., Zhang Y., Wang Q. Multiattribute utility function for a comprehensive health status classification system. Health Utilities Index Mark 2. Med Care. 1996 Jul;34(7):702–722. doi: 10.1097/00005650-199607000-00004. [DOI] [PubMed] [Google Scholar]
  24. Torres X., Arroyo S., Araya S., de Pablo J. The Spanish Version of the Quality-of-Life in Epilepsy Inventory (QOLIE-31): translation, validity, and reliability. Epilepsia. 1999 Sep;40(9):1299–1304. doi: 10.1111/j.1528-1157.1999.tb00861.x. [DOI] [PubMed] [Google Scholar]
  25. Wells G. A., Tugwell P., Kraag G. R., Baker P. R., Groh J., Redelmeier D. A. Minimum important difference between patients with rheumatoid arthritis: the patient's perspective. J Rheumatol. 1993 Mar;20(3):557–560. [PubMed] [Google Scholar]
  26. Wiebe S., Eliasziw M., Matijevic S. Changes in quality of life in epilepsy: how large must they be to be real? Epilepsia. 2001 Jan;42(1):113–118. doi: 10.1046/j.1528-1157.2001.081425.x. [DOI] [PubMed] [Google Scholar]
  27. Wiebe S., Rose K., Derry P., McLachlan R. Outcome assessment in epilepsy: comparative responsiveness of quality of life and psychosocial instruments. Epilepsia. 1997 Apr;38(4):430–438. doi: 10.1111/j.1528-1157.1997.tb01732.x. [DOI] [PubMed] [Google Scholar]
  28. Wright J. G., Young N. L. A comparison of different indices of responsiveness. J Clin Epidemiol. 1997 Mar;50(3):239–246. doi: 10.1016/s0895-4356(96)00373-3. [DOI] [PubMed] [Google Scholar]
  29. Wyrwich K. W., Tierney W. M., Wolinsky F. D. Further evidence supporting an SEM-based criterion for identifying meaningful intra-individual changes in health-related quality of life. J Clin Epidemiol. 1999 Sep;52(9):861–873. doi: 10.1016/s0895-4356(99)00071-2. [DOI] [PubMed] [Google Scholar]

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