Predicting the outcome of scitic t short-term follow-up Ptrick C A J Vroomen, M C T F M de Krom nd J A Knottnerus Originl ppers SUMMARY Bckground: The prognostic vlue of the clinicl findings elicited in the ptient presenting with scitic is unknown. Aim: To investigte whether history nd physicl exmintion findings cn predict outcome. Design of study: Prospective study of prognostic fctors. Setting: A smple of primry cre ptients with scitic. Method: Short-term fvourble outcome ws registered s improvement perceived by the ptient fter two weeks. Longterm filure ws defined s eventul surgery or lck of improvement fter three months. Results: The signs nd symptoms tht most consistently predicted n unfvourble outcome were: disese durtion of more thn 30 dys; incresed pin on sitting; nd more pin on coughing, sneezing or strining. The stright leg rising test nd, to lesser degree the reversed stright leg rising test, were the most consistent exmintion findings ssocited with poor outcome. Chnces of short-term improvement were lso relted to the body weight reltive to the length. Conclusion: The predictors in this study cn indicte the prognosis of ptients with scitic t n erly stge. Knowledge of these prognostic fctors my help to fine tune tretment decisions nd improve ptient selection in trils of conservtive therpy strtegies. Keywords: scitic; bck pin; outcome ssessment. P C A J Vroomen MD, PhD; M C T F M de Krom; nd J A Knottnerus, Deprtment of Clinicl Neurophysiology, Mstricht University Hospitl, Mstricht, Netherlnds. Address for correspondence Dr Ptrick C A J Vroomen, Deprtment of Neurophysiology, Mstricht University Hospitl, P Debyeln 25, PO Box 5800, 6202 AZ Mstricht, The Netherlnds. E-mil: pvr@sneu.zml.nl Submitted: 7 Februry 2000; Editor s response: 30 August 2000; finl cceptnce; 24 July 2001. British Journl of Generl Prctice, 2002, 52: 119-123. Introduction THE nturl course of scitic 22,17,23 is fvourble in most ptients nd the primry mngement chllenge is dequte pin control. However, some ptients do not improve even in the long term. If disc hernition is found to be the cuse of the scitic syndrome then ptients my become surgicl cndidtes. In ny cse, ptients with poor longterm outcome or eventul lumbo-scrl discectomy my be regrded s ptients with n unfvourble outcome of the reltively benign scitic syndrome. The question rises s to whether n eventul unfvourble outcome my be predicted t n erly stge. Only one study 3 hs ddressed the prognostic vlue of clinicl findings in the ptient with scitic. In this study, the clinicl dt were gthered retrospectively nd ptients included were selected becuse they hd undergone mgnetic resonnce imging. This introduces bis becuse the more severely ffected will hve hd higher likelihood of being included in the study. In this pper we present prospective study to find out whether clinicl findings t bseline could predict outcome. In ddition, the nturl course of the scitic syndrome (regrdless of the cuse) ws reconstructed. Method Study popultion Between Februry 1995 nd December 1996, 50 generl prctitioners (GPs) in Mstricht nd surrounding villges invited ptients to prticipte in study on scitic. Ptients were referred to the neurology deprtment of the Mstricht University Hospitl if they presented for the first time with n episode of scitic with pin intensity sufficient to justify further therpy. They hd to hve t lest two of the following signs nd symptoms: typiclly dermtoml pin distribution; incresed pin in the leg on coughing, sneezing or strining; decresed muscle strength; sensory loss; reflex loss; nd/or positive nerve root irrittion signs. Ptients with the following fctors were excluded: previous spinl surgery; concurrent Worker s Compenstion clims; pregnncy; unvilbility for follow-up visits (e.g. plns to move house); serious comorbidity or n indiction for immedite surgicl intervention; intrctble pin; rpid progression of presis; severe presis of limited durtion; or cud equin syndrome. This study ws performed concurrently with rndomised controlled tril of bed rest. 22 The study ws pproved by the institutionl review bord of the Mstricht University Hospitl, nd ll the ptients provided written informed consent. Bseline exmintions All subjects selected were exmined within two dys of refer- British Journl of Generl Prctice, Februry 2002 119
P C A J Vroomen, M C T F M de Krom nd J A Knottnerus HOW THIS FITS IN Wht do we know? The nturl course of scitic is fvourble in most ptients nd the primry mngement chllenge is dequte pin control. However, some ptients do not improve even in the long term. The question rises s to whether n eventul unfvourble outcome my be predicted t n erly stge. Wht does this pper dd? About one-third of ptients will hve recovered two weeks fter presenttion nd bout three-qurters fter three months. Surgery ws definite ltertion not only of the nturl course, but the course of scitic fter miniml conservtive therpy. A number of signs nd symptoms in the history nd physicl exmintion predict different types of outcome in ptients with scitic, e.g. n increse of pin on coughing, sneezing or strining is consistent indictor of poor prognosis. The predictors of this study indicte the prognosis in ptients with scitic t n erly stge, which my help to fine tune tretment decisions. rl by the GPs. A stright leg rising (SLR) test ws performed by rising the ptient s stright leg with the ptient in supine position. If this provoked typicl, dermtoml pin in the leg the test ws considered positive. This procedure followed the originl description of the test in the 1881 thesis by Forst, pupil of Lségue. The reversed SLR (known s the femorl nerve stretch test) ws performed with the ptient in the lterl recumbent position. After 15Þ retroflexion of the stright leg in the hip, the knee ws bent. If the ltter procedure intensifed or provoked the ptient s leg pin, the test ws considered positive. Presis ws tested s described by the Medicl Reserch Council. Light touch ws tested by softly stroking the skin in dermtoml ptterns, nd pin senstion by pplying the blunt nd shrp edges of plstic stick. The finger-to-floor distnce ws tested by hving the stnding ptient rech for the floor with full knee extension, nd the distnce between middle fingers nd the floor ws then mesured. A detiled description of investigtive technique nd the vribilities between observers re reported elsewhere. Three clsses of independent vribles were investigted for their prognostic vlue (Tble 1). An dditionl vrible ws included, indicting inclusion in the bed rest or wtchful witing group in the tril. Differences in the qulittive description of pin were ssessed t bseline, two weeks, nd 12 weeks, with the McGill Pin Questionnire, 11 in which ptients choose words tht best fit their pin, resulting in totl pin rting index. This ws directly monitored by n nonymous resercher. Two functionl sttus questionires: the modified Rolnd Disbility Scle, nd the revised Oswestry Low Bck Pin Questionnire, were completed by the ptients t bseline. 2,4,7,14 Outcome prmeters Ptients were seen by one outcome ssessor nd they completed questionnires t bseline nd fter two weeks nd 12 weeks. The ptients indicted whether their condition hd worsened, hd remined unchnged, hd improved or hd improved gretly. Mjor improvement fter two weeks ws defined s mjor improvement s reported by the ptient. Poor outcome fter three months ws defined s the bsence of ny improvement, or eventul surgery. To ssess the influence of defining surgery s poor outcome, we repeted the nlysis to predict poor outcome in the ptients treted conservtively throughout. Sttisticl nlysis First, bivrite nlysis ws performed for ll vribles in Tble 1. Dichotomous bseline prmeters were compred to dichotomous outcomes (mjor improvement fter two weeks nd fvourble outcome fter three months) by the χ 2 test for independent proportions. Continuous outcome mesures were compred for the two clsses by Student s t-test. A Person correltion coefficient ws clculted for the ssocitions between continuous vribles. Multiple logistic regression nlysis 9 ws used to predict fvourble outcome fter two weeks nd 12 weeks. Set I (Tble 1) ws modelled first, then Set II, incorporting the predictive vribles from the model of Set I. The predictors from Set I nd II were then used with the vribles of Set III. Presented in Tbles 3 nd 4 re ll vribles tht were significntly ssocited with outcome in the bivrite nlysis, or tht were significntly predictive of outcome in the finl reduced logistic regression models. Results Of 338 ptients referred by GPs for low bck pin, 227 hd scitic. Forty-four ptients, who hd slightly less severe disese (s scored on the visul nlogue scle by the observer) nd somewht lower score on the ffective dimension of the McGill Pin Questionnire, 10 declined to prticipte. Of the 183 finlly selected, two ptients who reported improvement did not return fter two weeks. After three months totl of 14 ptients hd been lost to follow-up; nine were unwilling to return, two hd moved, two hd incurred serious unrelted illnesses, nd one hd been imprisoned. Their bseline chrcteristics nd success rte fter two weeks were similr to the 169 remining ptients. The bseline chrcteristics of the 183 ptients selected re shown in Tble 1. The medin durtion of disese t bseline ws 16 dys, but more thn 30 dys for 26% of ptients. After two weeks, 36% of the ptients showed mjor improvement. After 12 weeks, 73% of ptients showed resonble to mjor improvement without surgery. Of the 49 ptients with poor outcome, 71% will hve undergone surgery one yer fter initil presenttion. In Tble 2, the second column shows the percentge of ptients with prticulr finding tht shows fvourble outcome t follow-up. The next column shows the percentge recovering when the finding ws bsent. In Figure 4, for exmple, 85% of ptients with positive SLR test recover, while 69% of ptients with negtive SLR recover. Decresed pin t night, the tendency to improve lredy t bseline, decresed pin on increse of pressure, nd higher Quetelet index (reflecting the weight divided by the squred length) re the fctors relted to fvourble out- 120 British Journl of Generl Prctice, Februry 2002
Originl ppers Tble 1. Ptient chrcteristics (n = 183). Set I: demogrphic % Set II: signs nd symptoms % Set III: physicl exmintion % Age 46 f Leg pin greter thn bck pin 69 Decresed lordosis 26 Mle sex 56 Sudden onset of pin 43 Finger-to-floor distnce >24 cm 41 Tertiry eduction 24 Cuse of pin known 33 Presis 18 Living lone 11 Pin worse t night 33 Hypesthesi 33 Employed 61 Proxysml pin 39 Hyplgesi 14 Previous scitic 37 Pin lredy improving 28 Ankle tendon reflex difference 15 Previous low bck pin 73 Observer s opinion 59 (m) Knee tendon reflex difference 9 Fmily history 32 Typiclly dermtoml pin 92 SLR test 71 Comorbidity 34 Incresed pin on pressure b 49 Reversed SLR test 24 Smokers 48 Pin on sitting 54 Vlleix points c 11 Active in sporting ctivities 44 Decresed pin on lying down 99 Kemp sign present d 41 Hs exercised bdominls 37 Decresed pin when upright 97 Nffziger sign present e 15 Quetelet index 25.2 f Subjective wekness 26 Questionnire results Subjective sensory loss 45 Revised Oswestry 28 f Cold senstions 30 Rolnd Disbility 5.3 f Presthesis in the leg 54 McGill Pin 19.4 f Disturbed urinry pssge Urinry incontinence 4 Helth worries 28 Complint severity scored on visul nlogue scle. b During coughing, sneezing or strining. c Tenderness long the scitic nerve. 5,20 d Pin on lteroflexion nd xil pressure of lumbr spine. 8,20 e Pin on compression of jugulr veins. 5,20 f Men vlues. Tble 2. Predictors of mjor improvement over following two weeks (n = 183). Clinicl findings Percentge showing improvement Crude Adjusted odds rtio odds rtio Present Absent (95% CI) (95% CI) b Most pin t night 25 42 0.5 (0.2 0.9) 0.4 (0.2 0.9) Alredy improving from bseline 53 30 2.7 (1.4 5.2) 2.9 (1.3 6.4) More pin on increse of pressure 24 47 0.4 (0.2 0.7) 0.3 (0.1 0.6) Finger-to-floor distnce 25cm 38 20 1.3 c 2.1 (1.0 4.3) Disturbed light touch senstion 45 32 1.8 c 2.5 (1.2 5.1) Quetelet index d 0.8 (0.79 0.96) 0.88 (0.78 0.98) Demonstrtes crude odds rtios, i.e. ssocitions between findings nd outcome in univrite logistic model. b These findings significntly contribute to prediction of the logistic regression model. The complete reduced model is presented. The intercept for this model is 2.59 (95% CI = 0.73 242). The presented djusted odds rtios re derived from the finl reduced multiple logistic regression model. c Non-significnt ssocition in the bivrite nlysis. d The Quetelet index is continuous mesure. The men Quetelet index in the group with mjor improvement ws 24.1, nd in the group without mjor improvement 25.8. The P-vlue for difference in mens ws 0.009. come t two weeks. For exmple, on verge, ptients with fvourble short-term outcome hd n index of 24.1, while those with n unfvourble outcome hd higher reltive body weight of 25.8 kg/m 2. When the independent predictive properties of the clinicl findings were investigted in multivrite nlysis, the finl optimlly predictive model incorported the finger-to-floor distnce nd disturbed light touch senstion, besides the four predictors from the nlysis. Tble 3 shows tht model tht best predicts outcome t three months contins only three vribles: durtion of disese of more thn 30 dys, positive SLR test, nd reversed SLR test. While trend towrds recovery t bseline nd more pin on increse of pressure were ssocited with fvourble outcomes, these findings did not contribute to logistic regression model. Even when ptients with eventul surgery were excluded from the nlysis, the durtion of disese nd the SLR test remined predictors of poor outcome. Discussion Success rtes of conservtive therpies for scitic vry from recovery for nerly ll ptients in the reports by Sl nd Sl 17,16 to 30% rte of mjor complints fter eight yers reported by Perce nd Moll. 13 In generl, scitic is considered to hve fvourble nturl course 18 nd in n pproximtion of the literture, it cn be stted tht threequrters of ptients with scitic will hve recovered fter between three nd five months. 19 This is confirmed by our study, which shows tht bout one-third of ptients will hve recovered two weeks fter presenttion nd bout threequrters fter three months. There is no ctul study of the nturl course of scitic. In ll studies to dte, intercurrent therpies hve been given tht my hve chnged the nturl course of scitic in some wy or nother, even in the cse of plcebo therpies. In this study, surgery ws definite ltertion of the nturl course. We demonstrte not the nturl course, but the course of scitic fter miniml conservtive therpy, ie. two weeks of bed rest in pproximtely hlf the ptients, nl- British Journl of Generl Prctice, Februry 2002 121
P C A J Vroomen, M C T F M de Krom nd J A Knottnerus Tble 3. Predictors of fvourble outcome fter 12 weeks. Clinicl findings Percentge showing improvement Crude Adjusted odds rtio odds rtio Present Absent (95% CI) (95% CI) Regrding eventul opertion s unfvourble outcome (n = 183) Durtion of pin 30 dys or less 40 23 0.3 (0.1 0.6) 0.1 (0.05 0.2) Alredy improving t bseline 53 30 2.9 (1.2 6.9) b More pin on increse of pressure 24 47 0.5 (0.2 0.97) b Positive SLR 69 85 0.4 (0.2 0.9) 0.4 (0.1 0.9) Positive reversed SLR 61 77 0.5 (0.2 0.97) 0.4 (0.2 0.9) Excluding ptients with eventul surgery from the nlysis (n = 156) Durtion of pin more thn 30 dys 69 93 0.2 (0.10 0.6) 0.1 (0.03 0.4) More pin on sitting 92 81 2.8 (0.99 7.8) 4.0 (1.20 13.2) Positive SLR 83 94 0.3 (0.10 1.3) 0.2 (0.05 0.8) The complete reduced models re shown. The intercept for the model with eventul surgery is 14 (95% CI = 5.2 38). b These fctors were relted to outcome in the bivrite nlysis but did not contribute to the predictive properties of the logistic regression model. gesics, nd hypnotics. The course ws considered unfvourble if the ptient perceived lck of improvement (in ny respect) t three months. Also, if t ny point the durtion nd intensity of pin nd decline in functionl sttus ws such tht chnge from miniml conservtive therpy to surgery ws considered necessry, both by the ptient nd the doctor treting them, the course ws considered unfvourble. The drwbck is tht both these spects of outcome re subjective nd my be influenced by psychosocil fctors nd by tretment preferences of the ptient nd treting physicin. The dvntge is tht outcome is presented in the mnner most relevnt to the ptient. Crrgee nd Kim hve previously studied the ssocition between clinicl findings nd outcome of scitic. 3 In their study with retrospective gthering of clinicl dt, durtion of disese of more thn six months, Worker s Compenstion clim, nd being in n older ge group, predicted poor outcome. The durtion of disese fetures s predictor of outcome in our study s well. Concurrent Worker s Compenstion clims were mong the exclusion criteri in our study, not only becuse the prognosis of this group my be different, but lso becuse the dignosis of scitic my be more troublesome. Older ge ws not poor prognostic sign in our study. Other studies hve focused on the outcome of surgery nd of rehbilittion fter surgery. 12 Fvourble outcome of surgery ws predicted by sedentry work, bsence of motor or sensory deficits, nd preopertive utotrction, 1 nd unfvourble outcome by bnorml hysteri nd hypochondrisis subscles of the Minnesot Multiphsic Personlity Inventory. 6,24 None of these fctors were relevnt in our study of miniml conservtive therpy for scitic. The scores of the Rolnd Disbility Scle, the Oswestry Low Bck Questionnire nd the McGill Pin Questionnire, were not relted to outcome. Our study shows tht number of signs nd symptoms in the history nd physicl exmintion predict different types of outcome in ptients with scitic. Our definition of scitic ws derived from the Dutch consensus sttement on scitic. It seems logicl tht trend towrds recovery t presenttion should predict fvourble short-term outcome. Similrly, when scitic hs been present for more thn 30 dys t presenttion, the chnces of improvement re diminished compred with shorter disese durtion. Of the signs nd sympotoms, n increse of pin on coughing, sneezing or strining is consistent indictor of poor prognosis. It could be hypothesised tht this symptom predicts poor outcome becuse it predicts eventul surgery. 21 On the contrry, n increse in pin on sitting predicts poor outcome in ptients who do not hve surgery. Previously, the SLR test hd been shown to predict poor outcome for low bck pin ptients; 15 however, this my hve been becuse positive SLR test is ssocited with scitic nd becuse scitic hs worse prognosis thn low bck pin. Even mong ptients with scitic, the SLR test is consistent indictor of poor prognosis. In ddition, mong ptients who do not hve surgery but who hve poor outcome, the SLR test is more frequently positive. Interestingly, weight reltive to length of the ptient is ssocited with short-term recovery. This my be direct cusl reltion in which cse strtegies to reduce weight my prove worthwhile lso for scitic ptients. Alterntively, reltive weight my be correlted with fctors such s degree of physicl ctivity, lifestyle, nd hypertension, which my explin the ssocition with outcome. Most conservtive interventions re ineffective for the mjority of ptients with scitic. 19 They my, however, hve n effect on prticulr subgroup, e.g. groups with prticulr prognosis. The predictors of this study indicte the prognosis in ptients with scitic t n erly stge, which my help to fine tune tretment decisions. For exmple, the decision to prescribe more extensive physicl therpy progrmme might tke into ccount the likelihood of future unfvourble outcome. It my lso improve ptient selection for trils of conservtive therpy strtegies. References 1. Brrios C, Ahmed M, Arrotegui JI, Bjornsson A. Clinicl fctors predicting outcome fter surgery for hernited lumbr disc: n epidemiologicl multivrite nlysis. J Spinl Disord 1990; 3: 205-209. 2. Beurskens AJ, de Vet HC, Koke AJ. Mesuring the functionl sttus of ptients with low bck pin. Assessment of the qulity of 122 British Journl of Generl Prctice, Februry 2002
Originl ppers four disese-specific questionnires. Spine 1995; 20(9): 1017-1028. 3. Crrgee EJ, Kim DH. A prospective nlysis of mgnetic resonnce imging findings in ptients with scitic nd lumbr disc hernition: correltion of outcome with disc frgment nd cnl morphology. Spine 1997; 22: 1650-1660. 4. Deyo RA: Comprtive vlidity of the sickness impct profile nd shorter scles for functionl ssessment in low bck pin. Spine 1986; 11: 951-954. 5. Herer AF. DeJong s The Neurologicl Exmintion. Chpter 47: Lesions cusing low bck pin with lumbo-scrl rdition. Phildelphi: JB Lippincott, 1992; 596-602. 6. Herron LD, Turner J, Clncy S, Weiner P. The differentil utility of the Minnesot Multiphsic Personlity Inventory. A predictor of outcome in lumbr lminectomy for disc hernition versus spinl stenosis. Spine 1986; 11: 847-850. 7. Hsieh CY, Phillips RB, Adms AH, Pope MH: Functionl outcomes of low bck pin: comprison of four tretment groups in rndomised controlled tril [see comments]. J Mnipultive Physiol Ther 1992; 15: 4-9. 8. Kemp A. Een nieuw symptoom bij prolps vn de tussenwervelschijf. Ned Tijdschr v Geneesk 1950; 94(II): 1750-1755. 9. Kleinbum DG. Logistic regression: self-lerning text. 1st edition. New York: Springer, 1994; 282. 10. Melzck R, Ktz J. The McGill Pin Questionnire: pprisl nd current sttus. In: Turk DC, Melzck R, (ed). Pin 1992; 152-168. 11. Melzck R, Ktz J: Pin mesurement in persons in pin. In: Wll PD, Melzck R, (ed). Textbook of pin. New York: Churchill Livingstone; 1994; 337-349. 12. Nykvist F, Alrnt H, Hurme M, Krppi SL. Clinicl findings s outcome predictors in rehbilittion of ptients with scitic. Int J Rehbil Res 1991; 14: 131-144. 13. Perce J, Moll JMH. Conservtive tretment nd nturl history of cute lumbr disc lesions. J Neurol Neurosurg Psychit 1967; 30: 13-17. 14. Rolnd M, Morris R. A study of the nturl history of bck pin. Prt I: development of relible nd sensitive mesure of disbility in low bck pin. Spine 1983; 8(2): 141-144. 15. Rolnd M, Morris R. A study of the nturl history of low bck pin. Prt II: development of guidelines for trils of tretment in primry cre. Spine 1983; 8(2): 145-150. 16. Sl JA. Nturl history nd non-opertive tretment of lumbr disc hernition. Spine 1996; 21(24 suppl): 2S-9S. 17. Sl JA, Sl JS, Herzog RJ. The nturl history of lumbr intervertebrl disc extrusions treted non-opertively. Spine 1990; 15(7): 683-686. 18. Stm J. Consensus over het lumboscrle rdiculire syndroom. Ned Tijdschr v Geneesk 1996; 140: 2661. 19. Vroomen PCAJ. The dignosis nd conservtive tretment of scitic. Mstricht: Dtwise/Krips; 1998; 1-139. 20. Vroomen PCAJ, de Krom MCTFM, Knottnerus JA. The consistency of the history nd the physicl exmintion in the ptient suspected of scitic. Spine 2000; 25: 91-96. 21. Vroomen PCAJ, Krom MCTFM, Knottnerus JA. When does the ptient suspected of lumboscrl nerve root compression undergo lumboscrl discectomy? J Neurol Neurosurg Psych 2000; 68, 75-79. 22. Vroomen PCAJ, Krom MCTFM, Wilmink JT, et l. Lck of effectiveness of bed rest for scitic. N Eng J Med 1999; 340: 418-423. 23. Weber H, Holme I, Amlie E. The nturl course of cute scitic with nerve root symptoms in double-blind plcebo-controlled tril evluting the effect of piroxicm. Spine 1993; 18: 1433-1438. 24. Wiltse LL, Rocchio PD. Preopertive psychologicl tests s predictors of success of chemonucleolysis. J Bone Joint Surg 1975; 57(4): 478-483. British Journl of Generl Prctice, Februry 2002 123