Act Orthop. Belg., 2015, 81, 23-29 ORIGINAL STUDY Use of Clscn for improving osteoporosis cre in the older ptient dmitted with hip frcture Gijs De Klerk, J. Hn Hegemn, Detlef Vn Der Velde, Jo Vn Der Plen, Henk J. Ten Duis From Deprtment of Trumtology, Ziekenhuisgroep Twente, Almelo, the Netherlnds nd Deprtment of Epidemiology, Medisch Spectrum Twente, Enschede nd Deprtment of Surgery, University Medicl Center Groningen, Groningen To determine whether one minerl density mesurement using the Clscn successfully predicts the ctul one minerl density, s mesured y dulenergy X-ry sorptiometry. We included ll ptients 65 yers with hip frcture screened on osteoporosis y oth dul-energy X-ry sorptiometry nd the Clscn during the period April 2008 to April 2011. The one minerl density ws expressed s T-score. For the Clscn T-score, thresholds were defined such tht ptients with nd without osteoporosis could e identified with 90% certinty. Ptients with Clscn T-score ove the upper threshold were considered to e non-osteoporotic nd those with Clscn T-score elow the lower threshold considered osteoporotic. Ptients whose Clscn T-score ly etween the two thresholds could only e clssified y mens of DXA. The correltion etween dul-energy X-ry sorptiometry nd the Clscn ws 0.61. The Clscn identified pproximtely 25% of ptients s osteoporotic nd 25% s non-osteoporotic. The upper threshold ws found to e -1.8SD nd the lower threshold -3.5SD. Osteoporosis screening y dul-energy X-ry sorptiometry hd een crried out in 44% of ptients. This percentge could theoreticlly rise to > 70% if the Clscn is implemented in osteoporosis screening, while costs of such screening pper to e lower, s long s sufficient numer of ptients re screened. Keywords : Clscn ; dul x-ry sorptiometry ; osteoporosis ; hip frcture. INTRODUCTION Hip frctures re mjor prolem in helth cre. Ech yer in the Netherlnds pproximtely 17,000 ptients re dmitted with hip frcture nd this numer is set to increse in the coming yers (4,17). The costs of treting this ptient group mount to out 391 million euros per yer. Qulity of life is clerly reduced in this ptient group nd optimizing their cre is importnt, oth to limit costs nd improve qulity of life (14,21). An importnt prt of such cre optimiztion is screening for osteoporosis (3). Osteoporosis is mjor risk fctor for hip frcture nd tretment of osteoporosis cn prevent 40% of susequent osteoporotic frctures (16). In our hospitl, osteoporosis screening is stndrd prt of the cre pln for older n Gijs De Klerk. n J. Hn Hegemn. n Detlef Vn Der Velde. n Jo Vn Der Plen. n Henk J. Ten Duis. Deprtment of Trumtology, Ziekenhuisgroep Twente, Almelo, the Netherlnds nd Deprtment of Epidemiology, Medisch Spectrum Twente, Enschede nd Deprtment of Surgery, University Medicl Center Groningen, Groningen. Correspondence : Gijs de Klerk, Zilvermeeuw 1, 7600SZ Almelo, The Netherlnds. E-mil : gijsdeklerk@hetnet.nl 2015, Act Orthopædic Belgic. No enefits or funds were received in support of this study. The uthors report no conflict of interests.
24 g. de klerk, j. h. hegemn, d. vn der velde, j. vn der plen, h. j. ten duis ptients with (hip) frcture, nd is specified in the cre pthwys of the Geritric Trum Unit (GTU). At the GTU, the cre for older frcture ptients is continuously evluted nd optimized, which helps improve the qulity of cre (12). An interim evlution reveled tht only 40% of ptients dmitted to the GTU were ctully screened for osteoporosis. This percentge ws lower thn expected other studies hve demonstrted levels of 70% nd must e incresed in order to provide ptients with mximum effective cre (13,23). It my well e possile to chieve this using peripherl dul-energy X-ry sorptiometry (pdxa). Erlier studies hve shown tht pdxa nd xil dul-energy X-ry sorptiometry (DXA) hve equl predictive vlue for estimting the risk of frcture t ny skeletl site (15,18). One of these peripherl mesurement devices is the Clscn, which mesures the BMD t the clcneus. Compred to DXA, the Clscn is smller, cheper, portle, results in lower rdition dose nd cn e pplied on the hospitl wrd (20). This enles osteoporosis screening to e conducted during the ptient s sty in hospitl, which is ig dvntge over DXA. If mesurement of one minerl density (BMD) using pdxa proves to e vlid technique, the percentge of ptients tht re screened for osteoporosis will most likely increse. The im of this study ws to determine whether BMD mesurement using pdxa successfully predicts the ctul BMD, s mesured using DXA, in ptients with hip frcture. PATIENTS AND METHODS This is retrospective study conducted in non-cdemic teching hospitl in the Netherlnds. All ptients 65 yers who were dmitted to the GTU with hip frcture from April 2008 to April 2011 nd who hd undergone osteoporosis screening t our frcture prevention clinic (FP clinic) were eligile for inclusion in this study. Exclusion criteri for osteoporosis screening t the FP clinic were dementi, pthologicl frcture, referrl to nother specilty, recent screening for osteoporosis, or n ddress outside the hospitl s drwing re. Ptients were included retrospectively y serching in the electronic hospitl informtion system for tretment code 820 (hip frcture) of the Interntionl Clssifiction of Diseses (ICD-9) (7). Ptients re screened t our FP clinic with oth DXA nd pdxa. We identified totl of 455 ptients with hip frcture. Of these 455 ptients, 124 were excluded. We found tht 108 of the 331 ptients tht should hve een screened for osteoporosis with oth DXA nd pdxa hd undergone oth scns (Fig. 1). Our study popultion therefore consisted of 108 ptients. DXA is the golden stndrd for mesuring BMD (11,15). The densitometer used t our FP clinic is the Hologic Discovery A (Hologic, Bedford, MA, USA). The scn protocol tkes out 20 minutes nd the instrument is clirted dily with phntom. BMD is mesured t the lumr spine nd the left hip nd expressed s T-score, which is comprison etween the BMD mesured nd pek one density. According to the World Helth Orgniztion s definition, T-score -2.5SD indictes the presence of osteoporosis ; T-score etween -1SD nd -2.5SD indictes the presence of osteopeni ; nd T- score > -1SD is considered to e norml (1). The pprtus used for pdxa ws the Clscn (DXL Clscn, Demetech AB, Soln, Sweden). The Clscn comines DXA nd lser technology, therey llowing the BMD to e mesured t the clcneus (19,20). The optiml scn position is determined utomticlly. The scn protocol for the Clscn tkes out 5 minutes nd the instrument is clirted utomticlly efore ech mesurement. The results re lso expressed s T-score nd re ville immeditely following the scn. To determine the suitility of Clscn s replcement for DXA, we compred the vlues otined with the Clscn with those otined with DXA. A high correltion would men tht the Clscn is vlid mesuring instrument. By clculting thresholds for the Clscn T-score, we were le to predict when DXA scnning might not e necessry. These thresholds for the Clscn T-score were defined such tht osteoporotic ptients could e identified with 90% sensitivity nd specificity ; in other words, 90% of ptients with osteoporosis would hve Clscn T-score elow the upper threshold nd 90% of ptients without osteoporosis would hve Clscn T-score ove the lower threshold. Similrly, ptients with Clscn T-score elow the lower threshold could e clssified s hving osteoporosis, nd ptients with Clscn T-score ove the upper threshold s not hving osteoporosis. Ptients with Clscn T- score etween the two thresholds could only e clssified y mens of DXA (5). A complete cost effectiveness nlysis with the dt presented here ws not possile since the study is retrospective nd the Clscn nd DXA scns were oth performed t the FP clinic. However, it ws possile to
use of clscn for improving osteoporosis cre 25 t the wrd, during dmission to the hospitl. These costs cn e split into non-recurring expense of 20,000 for purchsing the Clscn nd the yerly mintennce costs of 2,500. As there is no need for specilised personnel to operte the Clscn nd it tkes only 5 minutes per ptient, the Clscn cn e operted y the nursing stff t the wrd. Therefore, this will not incur dditionl costs. Ptients who could not e dequtely clssified using the Clscn T-score would require further scnning using DXA, which costs 75 per ptient. Sttisticl nlysis ws performed using SPSS softwre. The results re expressed s men nd stndrd devition or rnge. The Person correltion coefficient ws used to determine the reltionship etween BMD mesured using DXA nd BMD mesured using the Clscn. The thresholds for the Clscn were clculted using contingency tles. The 95% confidence intervls were lso clculted. RESULTS FP-clinic : frcture prevention clinic. DXA : dul-energy X-ry sorptiometry. Fig. 1. Flow chrt showing ptients 65 yers who were dmitted to our hospitl with hip frcture nd who were screened for osteoporosis t the FP-clinic. clculte the costs of osteoporosis screening using DXA. In our clinic, these costs mount to 75 per ptient. We were lso le to clculte the theoreticl costs if the Clscn hd een used in the screening for osteoporosis Of the 108 ptients, 31 were mle nd 77 were femle. The men ge ws 77.5 yers (SD 7.3). For BMD mesurement using DXA, the men T-score ws -1.91 SD (rnge : -5.2 to 1.1SD) nd for the Clscn -2.40SD (rnge : -5.5 to 1.3SD). The correltion etween DXA nd the Clscn ws r = 0.61 (p < 0.001), which mens tht 36% of the vrince in DXA could e ccounted for y the Clscn T- score. In totl, sed on the DXA mesurement, 35 ptients could e clssified s hving osteoporosis nd 73 s not hving osteoporosis. Of these 35 osteoporotic ptients, 91.4% (95%CI : 77-98%) hd Clscn T-score -1.8SD. In order to correctly clssify 90% of the ptients with osteoporosis, the upper threshold for the Clscn T-score ws set t -1.8SD. Of the 73 non-osteoporotic ptients, 89% (95%CI : 80-95%) hd Clscn T-score > -3.5SD. In order to correctly clssify out 90% of the ptients without osteoporosis, the lower threshold for the Clscn T-score ws set t -3.5SD. Using these threshold vlues, 25 ptients with Clscn T-score -3.5SD were considered to e osteoporotic nd 32 ptients with Clscn T-score > -1.8SD were considered to e non-osteoporotic. Therefore, 57 of the 108 ptients (53%) could e clssified on the sis of the Clscn T-score (Fig. 2, Tle I).
26 g. de klerk, j. h. hegemn, d. vn der velde, j. vn der plen, h. j. ten duis DXA : dul-energy X-ry sorptiometry. Lowest T-score : Lowest T-score mesured with DXA. c WHO : World Helth Orgniztion. Fig. 2. Reltionship etween Clscn T-score nd DXA T-score. In this figure the thresholds for the Clscn re determined ccording to the WHO c definition for osteoporosis (T -2.5SD). As shown in the figure, 91.4% of the osteoporotic ptients hve Clscn T-score -1.8SD nd 89% of the non-osteoporotic ptients hve Clscn T-score > -3.5SD. Tle I. Clcultion of the thresholds for the Clscn T-score Lower threshold Clscn T-score T -3.5SD Upper threshold Clscn T-score T -1.8SD Yes No Yes No DXA Yes 17 18 32 (91.4%) 3-2.5SD No 8 65 (89%) 44 29 DXA : dul-energy X-ry sorptiometry. This is the T-score mesured using DXA, wherey osteoporosis is defined s T-score -2.5SD. Tle II shows the theoreticl costs of osteoporosis screening with or without use of the Clscn. This tle clerly shows tht ecuse of the reltively high purchsing costs of the Clscn, screening will only ecome cheper if sufficient ptients per yer re screened for osteoporosis. More specificlly, using the Clscn will mke osteoporosis screening cheper if the numer of ptients screened for osteoporosis ech yer exceeds 200.
use of clscn for improving osteoporosis cre 27 Tle II. Comprison of costs of DXA nd Clscn 100 200 300 DXA CALSCAN DXA CALSCAN DXA CALSCAN yer 1 7500 23525 15000 27050 22500 30575 yer 2 15000 29300 30000 36350 45000 43400 yer 3 22500 35075 45000 45650 67500 56225 yer 4 30000 40850 60000 54950 90000 69050 yer 5 37500 46625 75000 64250 112500 81875 This tle shows the totl costs in euro per yer for screening on osteoporosis with DXA compred to the costs for screening on osteoporosis with the Clscn. These costs re expressed for different numer of ptients screened every yer. DXA: dul-energy X-ry sorptiometry. Numer of ptients screened on osteoporosis every yer. DISCUSSION This study shows tht the Clscn is vlid mesuring instrument. We hve shown tht using the Clscn T-score we were le to correctly clssify 53% of ptients s either osteoporotic or non-osteoporotic. In order to put the Clscn to use in osteoporosis screening, it is necessry to clculte thresholds. In the current study the vlues of these thresholds were -1.8SD nd -3.5SD. Erlier studies hve suggested tht the vlue for the upper threshold should lie etween -1.3 nd -1.4SD nd the vlue of the lower threshold etween -2.7 nd -3.2SD (8,10,20). This difference in threshold vlues cn e explined y the fct tht the ptients in these erlier studies were, on verge, younger thn those in the current study. As ptients get older, their men BMD will go down. As consequence, the vlues of the thresholds will lso go down. A smll clinicl study in ptients ged etween 72 nd 98 yers found the vlue of the lower threshold to e -3.2SD (8). This hs lso een confirmed y mthemticl model which specifies tht, t the ge of 75, the vlue of the upper threshold should e -1.9SD nd tht of the lower threshold -3.2SD (9). The vlues of the thresholds clculted here re therefore similr to those found in other studies, provided they re corrected for ge. However, since the thresholds for the Clscn used in this study were sed on reltively smll study popultion, they cnnot utomticlly e pplied to ll ptients with hip frcture. To this end, lrger prospective studies re needed. Another importnt finding in this study ws tht only 44% (147/331) of the ptients 65 yers with hip frcture hd een screened for osteoporosis, despite the fct tht osteoporosis screening is stndrd prt of the cre pln for ptients with such frcture. Theoreticlly, this percentge could rise to 70% or more if the Clscn were to e used for osteoporosis screening ; fter ll, 53% could e correctly clssified using the Clscn T-score nd of the other ptients 44% would e screened t the FP clinic. We were unle to relily determine the reson why only 44% of ptients were screened for osteoporosis. Apprently, 42% of ptients did not show up to the ppointment t the FP clinic or were mistkenly not given n ppointment in the first plce. For the other 58% of ptients we could not discover the reson they were not seen t the FP clinic. One reson might e tht this less moile ptient group experiences n extr visit to the clinic s eing too urdensome. Another explntion might e tht DXA cn only e crried out once ptients re sufficiently moile, resulting in dely of severl months efore the scn. With such time hving pssed since the initil frcture, some ptients will e less inclined to pprecite the enefit of osteoporosis screening. A theoreticl dvntge of osteoporosis screening using the Clscn on the hospitl wrd is tht, for 25% of ptients, the dignosis of osteoporosis cn lredy e mde during the hospitl sty nd nti-osteoporosis mediction cn e strted immeditely in this group of ptients. This could well prove to e eneficil since the mximum effect of
28 g. de klerk, j. h. hegemn, d. vn der velde, j. vn der plen, h. j. ten duis nti-osteoporotic drugs is not reched until fter three months nd most successive frgility frctures occur within one yer (2,22). In ddition, it would pper possile to reduce the costs of osteoporosis screening using the Clscn for such screening. Prospective studies re needed to sustntite these dvntges. A limittion of this study is the possiility of selection is ecuse DXA nd Clscn were not performed during dmission to the hospitl, ut in n outptient setting t the FP Clinic. Therefore, only 108 of the 331 ptients who should hve een screened for osteoporosis were ctully screened with oth devices. However, ecuse in most hospitls it is not possile to otin DXA-scn during dmission to the hospitl, ecuse of logistic nd ptient relted (for exmple : immoility) resons, it is difficult to prevent this selection is. CONCLUSION For the time eing, DXA remins the golden stndrd for mesuring BMD. However, despite well-orgnized osteoporosis cre only 44% of ptients were screened for osteoporosis. In this study we demonstrte tht the Clscn ppers to e vlid mesuring instrument tht could e used to increse the percentge of ptients undergoing screening for osteoporosis to more thn 70%. An dditionl dvntge is tht 25% of ptients could e strted on nti-osteoporosis mediction during their hospitl sty. Acknowledgements The uthors would like to thnk Mrs. Ingeorg ter Beek nd Mrs. Henriette Kroeze, osteoporosis nurse specilists, for their work nd for the inclusion of their ptients t the FP clinic. We lso thnk Prof. Loek P.H. Leenen, trum surgeon t the University Medicl Center Utrecht, for criticlly reding through the mnuscript nd providing vlule comments. References 1. Assessment of frcture risk nd its ppliction to screening for postmenopusl osteoporosis. Report of WHO Study Group, 1994, p 1-129. World Helth Orgniztion technicl report series 843. 2. Informtorium medicmentorum. http://www.knmp.nl. 3. Kwliteitsinstituut voor de gezondheidszorg CBO. Richtlijn Osteoporose en frctuurpreventie derde herziening. Alphen n den Rijn : Vn Zuiden Communictions ; 2011. p 1-221. 4. Ntionl Komps Volksgezondheid. 20 ugustus 2008. Heupfrcturen smengevt. http://www.ntionlkomps.nl/gezondheid-en-ziekte/ ziekten-en-ndoeningen/ewegingsstelsel-en-indweefsel/ heupfrctuur/heupfrcturen-smengevt/. 5. Ntionl Osteoporosis Society. Position sttement on the use of peripherl x-ry sorptiometry in the mngement of osteoporosis. Bth, UK : NOS, 2004. 6. Rijksinstituut voor Volksgezondheid en Milieu RIVM. Kosten vn Ziekten in Nederlnd 2005. http://www.kostenvnziekten.nl/. 7. World Helth Orgniztion. Interntionl Clssifiction of Diseses (ICD), version 2007. http://www.who.int/clssifictions/icd/en/. 8. Alertsson D, Mellstrom D, Petersson C et l. Hip nd frgility frcture prediction y 4-item clinicl risk score nd moile heel BMD : women cohort study. BMC musculoskeletl disorders 2010 ; 11 : 55. 9. Blke GM, Chinn DJ, Steel SA et l. A list of devicespecific thresholds for the clinicl interprettion of peripherl x-ry sorptiometry exmintions. Osteoporos Int 2005 ; 16 : 2149-56. 10. de Klerk G, vn der Velde D, vn der Plen J et l. The usefulness of dul energy X-ry nd lser sorptiometry of the clcneus versus dul energy X-ry sorptiometry of hip nd spine in dignosing mnifest osteoporosis. Arch Orthop Trum Surg 2009 ; 129 : 251-7. 11. Estell R. Tretment of postmenopusl osteoporosis. N Engl J Med 1998 ; 338 : 736-46. 12. Folert E, Smit R, vn der Velde D et l. Multidisciplinry integrted cre pthwy for elderly ptients with hip frctures : implementtion results from Centre for Geritric Trumtology, Almelo, The Netherlnds. Ned Tijdschr Geneeskd 2011 ; 155 : A3197. 13. Hegemn JH, Willemsen G, vn Nieuwpoort J et l. Effective trcing of osteoporosis t frcture nd osteoporosis clinic in Groningen ; n nlysis of the first 100 ptients. Ned Tijdschr Geneeskd 2004 ; 148 : 2180-5. 14. Lips P, vn Schoor NM. Qulity of life in ptients with osteoporosis. Osteoporos Int 2005 ; 16 : 447-55. 15. Mrshll D, Johnell O, Wedel H. Met-nlysis of how well mesures of one minerl density predict occurrence of osteoporotic frctures. BMJ 1996 ; 312 : 1254-9. 16. Nkmur T, Liu JL, Morii H et l. Effect of rloxifene on clinicl frctures in Asin women with postmenopusl osteoporosis. J Bone Miner Met 2006 ; 24 : 414-8. 17. Sltzherr TP, Borghns HJ, Bkker RH et l. Proximl femur frctures in the elderly in The Netherlnds during the period 1991-2004 : incidence, mortlity, length of hospitl sty nd n estimte of the cre cpcity needed in the future. Ned Tijdschr Geneeskd 2006 ; 150 : 2599-604.
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