Assessment of Depression in Multiple Sclerosis. Validity of Including Somatic Items on the Beck Depression Inventory II

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1 Assessment of Depression in Multiple Sclerosis Vlidity of Including Somtic Items on the Beck Depression Inventory II Peggy Crwford, PhD; Noh J. Webster, MA Signs nd symptoms of multiple sclerosis (MS) my overlp with those of depression, common comorbidity. This study explored whether inclusion of somtic items on the Beck Depression Inventory-II (BDI-II) flsely elevted scores in clinicl smple of 557 dults with MS evluted by the helth psychology service within n MS center. Our smple s BDI-II responses were subjected to explortory fctor nlysis, nd the results were compred with those reported in the BDI-II mnul. Anlyses were then conducted to compre ptients who identified ftigue s their worst MS symptom with those who did not nd to compre those with high nd low levels of ftigue nd dytime sleepiness in terms of totl BDI-II score, percentge contribution of specific somtic items (ie, tiredness or ftigue) to totl BDI-II score, nd the sum contribution of the somtic-ffective fctor to the BDI-II score. Respondents who reported ftigue s their worst MS symptom nd those who did not hd lmost identicl BDI-II scores. Among ptients reporting ftigue s their worst symptom, only the loss of energy item ws significntly higher, s ws the tiredness or ftigue item mong ptients with severe ftigue. Percentge contribution of the somtic-ffective fctor to the totl BDI-II score did not differ significntly by the presence of ftigue s the worst MS symptom or level of dytime sleepiness. In conclusion, somtic items do not necessrily confound depression scores for individuls with MS nd should be retined when using the BDI-II to ssess depression in this popultion. Int J MS Cre. 2009;11: From the Division of Behviorl Medicine nd Clinicl Psychology, Cincinnti Children s Hospitl Medicl Center, Cincinnti, OH, USA (PC); nd Deprtment of Sociology, Cse Western Reserve University, Clevelnd, OH, USA (NJW). At the time this study ws conducted, Dr. Crwford ws ffilited with the Clevelnd Clinic, Clevelnd, OH, USA. Correspondence: Peggy Crwford, PhD, Division of Behviorl Medicine nd Clinicl Psychology, Cincinnti Children s Hospitl Medicl Center, 3333 Burnet Ave., MLC 3015, Cincinnti, OH ; e-mil: Peggy.Crwford@cchmc.org. Depression is very common in individuls with multiple sclerosis (MS), with n estimted lifetime prevlence rnging from 47% to 54%. 1 In MS ptients, depression hs been ssocited with decresed dherence to medicl regimens, 2 incresed risk of suicide, 3 nd decresed qulity of life. 4 In light of this high prevlence nd ssocited morbidity, the dignosis nd tretment of depression in individuls with depression is criticl clinicl issue. Accurte dignosis of depression in ptients with comorbid medicl disorders such s MS cn be difficult becuse of the potentil for overlp of symptoms in these conditions. This is n especilly significnt problem in MS becuse so mny individuls experience disese-relted symptoms such s ftigue, reduced energy, sleep difficulties, psychomotor retrdtion, nd decresed concentrtion. Becuse of this overlp, scores on scles ssessing depression in those with MS could be flsely elevted, potentilly resulting in overdignosis nd unnecessry tretment of depression. Previous studies hve exmined the reltionship between depression nd somtic items on the originl version of the Beck Depression Inventory (BDI) in MS ptients. Mohr nd collegues 5 compred the percentge contribution (reltive scores) of ech item on the BDI cross ptients with MS, ptients dignosed with mjor depressive disorder (MDD), nd norml college students. They considered n item to be confounded by MS-relted symptoms if its contribution to the totl BDI score ws significntly greter in the MS group thn in the other two groups. They found tht three items work difficulty, ftigue, nd concerns bout helth met this criterion nd recommended eliminting these items 167

2 Crwford nd Webster from the BDI when using it with MS ptients. In 1999 study, Aikens nd collegues 6 compred reltive scores for eight somtic BDI items with demogrphic vribles nd BDI totls s covrites cross ptients with MS, ptients with other medicl disorders (dibetes nd chronic pin), psychitric ptients with MDD, nd helthy controls. They found no significnt differences between groups on somtic items. The only significnt difference found ws on the item ssessing work bility, with MS ptients hving more difficulty with work thn helthy controls. On the bsis of their results, they recommended using the complete BDI when ssessing depressive symptoms in ptients with MS. To our knowledge, no comprble study of the use of the BDI in ptients with MS hs been conducted since the inventory ws revised in 1996 to be consistent with the Dignostic nd Sttisticl Mnul of Mentl Disorders (Fourth Edition) (DSM-IV). Four items (weight loss, body imge chnge, somtic preoccuption, nd work difficulty) were dropped from the originl BDI nd replced in the BDI-II with four new items (gittion, worthlessness, concentrtion difficulty, nd loss of energy) in order to include symptoms typicl of severe depression. 7 The primry im of the present study ws to determine whether inclusion of somtic items on the BDI-II flsely elevtes scores in lrge clinicl smple of MS ptients, mny of whom were referred specificlly for evlution of depression. It ws hypothesized tht inclusion of somtic items would not flsely elevte totl scores on the BDI-II becuse somtic symptoms re commonly experienced s prt of depression even for those who do not hve physicl disorder. We exmined the somtic component further by compring ptients who identified ftigue s their worst MS symptom with ptients who identified other symptoms s their worst. In ddition, we exmined specific mesures of somtic symptoms, specificlly ftigue nd dytime sleepiness. Methods Smple Prticipting in this study were 557 ptients with confirmed dignosis of MS who were self-referred or referred by member of the interdisciplinry tem to the helth psychology service t the Clevelnd Clinic s Mellen Center for Multiple Sclerosis Tretment nd Reserch. Most ptients were referred for evlution nd tretment of distress, including depression, difficulty coping, nd stress-relted increses in MS symptoms. The demogrphic, MS-relted, nd psychologicl chrcteristics of the study smple re presented in Tble 1. The 557 prticipnts hd men ge of 42.6 yers, with rnge of 18 to 74 yers. Of the totl, 77% (428) were femle, 81% (452) were white, 67% (369) hd t lest some college eduction, nd 58% (320) were mrried. Thirty-eight percent (209) reported working fulltime, 12% (66) worked prt-time, nd 51% (282) were not employed. Twenty-six percent (144) were currently receiving disbility benefits, nd nother 14% (76) were pplying for such benefits. In terms of MS, the verge time since dignosis ws 5.7 yers, rnging from less thn 1 yer to 43 yers, nd 76% (421) hd been dignosed with relpsing-remitting MS. Bsed on the BDI-II, 30% of the prticipnts were minimlly depressed, 19% were mildly depressed, 27% were modertely depressed, nd 24% were severely depressed. Of the totl smple, 77% (429) reported current depression or history of depression, nd 27% (149) hd primry psychitric dignosis of MDD. Only 51% (280) hd been prescribed psychotropic mediction nd seen mentl helth professionl. Another 14% (76) of those with history of depression hd seen mentl helth professionl, 21% (119) hd been on mediction, nd 14% (80) reported no mentl helth tretment. Over hlf (52%, 290) of the ptients were currently tking ntidepressnts, nxiolytics, or both; 20% (109) hd discontinued such medictions, nd 28% (156) hd no history of tking such medictions. Dt Collection Dt collection occurred s prt of ptient evlution by the helth psychology service locted in the MS center. Evlution included review of medicl records for demogrphic nd disese-relted informtion, clinicl interview for dditionl disese-relted informtion nd mentl helth history, nd completion of self-report mesures including the BDI-II. A subsmple (n = 155) lso completed the Ftigue Severity Scle (FSS) nd the Epworth Sleepiness Scle (ESS). This study nd ll dtcollection procedures were pproved by the institutionl review bord t the Clevelnd Clinic. Mesures Depression The BDI-II is 21-item instrument mesuring the presence nd severity of depressive symptoms. 7 Ech of 168

3 Beck Depression Inventory nd MS Tble 1. Chrcteristics of the study smple (N = 557) Chrcteristic Demogrphic Age, y Vlue Men (SD) 42.6 (10.3) Rnge Rce/ethnicity, % white 81.1 Sex, % femle 76.8 Eduction level Medin Rnge At lest some college, % 66.7 Mritl sttus, % mrried 57.5 Employment sttus, % Not employed 50.6 Employed prt-time 11.8 Employed full-time 37.5 Disbility sttus, % receiving or 39.6 pplying for disbility benefits 3 (some college) 1 (less thn high school) to 6 (postgrdute degree) MS-relted Durtion of MS, y Men (SD) 5.7 (6.7) Rnge <1 43 MS course, % relpsing-remitting 76.4 Chrcteristic Psychologicl Self-reported history of or current depression, % Primry psychitric dignosis of MDD, % Vlue Depression (BDI-II score) Men (SD) 20.8 (10.5) Rnge 1 53 Severity ctegory, % 0 13 (miniml) (mild) (moderte) (severe) 23.7 Antidepressnt/nxiolytic use, % Current 52.3 Previous 19.6 Never 28.1 Tretment history, % Mentl helth professionl 13.7 Mediction only 21.4 Both mentl helth professionl 50.5 nd mediction No tretment 14.4 Abbrevitions: BDI-II, Beck Depression Inventory II; MDD, mjor depressive disorder; MS, multiple sclerosis. Eduction level scle: 1 = less thn high school; 2 = generl equivlency diplom or high school diplom; 3 = some college or 2-yer degree; 4 = 4-yer college degree; 5 = some postgrdute work; 6 = postgrdute degree. the 21 items is rted on four-point scle rnging from 0 to 3, for mximum totl score of 63. In ddition to using BDI-II score s continuous vrible, this study broke depression down into four ctegories of severity ccording to totl BDI-II score, using the scle presented in the BDI-II mnul: 0 13 = miniml; = mild; = moderte; = severe. In generl, the BDI- II requires between 5 nd 10 minutes to complete. 7 Ftigue nd Dytime Sleepiness Stndrdized instruments were used to obtin detiled informtion on levels of ftigue nd dytime sleepiness. The FSS is nine-item stndrdized mesure with items scored on scle rnging from 1 (completely disgree) to 7 (completely gree). 8 An verge score cross the nine items ws clculted by dividing the totl FSS score by the number of items. This men composite ws used to split the smple into two groups: ptients with scores of 4 or higher, indicting severe ftigue, nd those with scores below 4. Dytime sleepiness ws mesured using the ESS, consisting of eight items scored from 0 (no chnce of dozing) to 3 (high chnce of dozing). 9 A totl dytime sleepiness score ws clculted by summing responses to the eight items. As with ftigue, the smple ws divided into two groups: those with sleepiness scores of 10 or higher, level considered bnorml, nd those with scores below 10. Ftigue Identified s Worst MS Symptom During the clinicl interview, ptients were sked to report their worst MS symptom in n open-ended formt. For the purposes of this study, the responses were grouped into two ctegories: 1) ftigue nd 2) ll other symptoms. 169

4 Crwford nd Webster Dt Anlytic Procedures Vlidtion of BDI-II Fctors in MS Smple The first prt of the dt nlytic strtegy involved conducting explortory fctor nlysis (EFA) on the BDI-II in order to vlidte its mesurement structure in our smple of MS ptients. The EFA ws conducted using principl xis fctoring nd direct oblimin rottion, which llowed for correltions between the fctors. Three seprte nlyses were conducted to constrin the number of fctors to 1, 2, nd 3, with the pproprite number of fctors determined by n exmintion of the residuls (lowest percentge greter thn 0.05), interpretbility of fctors, nd the scree plot. The results of our EFA (number of fctors, primry nd secondry fctor lodings) were compred with the results obtined nd reported on by Beck et l. 7 in smple of 500 outptient psychitric ptients. We present the fctor lodings from the EFA nlysis s well s those obtined by Beck et l. Additionlly, for our smple we present the percentge of vrince explined by the fctor(s), the relibility (Cronbch α), nd vlidity (correltion with possibly relted concept). Percentge Contribution to BDI-II Score Responses to the items mking up the somtic-ffective fctor were summed nd divided by ech ptient s totl BDI-II score to clculte the fctor s percentge contribution to the totl BDI-II score. We lso clculted the percentge contribution to the totl BDI-II score of ech of the three items most likely to be relted to ftigue (loss of energy, chnges in sleeping ptterns, nd tiredness or ftigue) by dividing the score of ech item by the ptient s totl BDI-II score. A series of one-wy nlyses of vrince (ANOVAs) with Bonferroni post hoc tests were conducted to exmine men differences cross the four ctegories of depression severity in percentge contribution to totl BDI-II score of 1) the somtic-ffective fctor nd 2) ech of the three items ddressing ftigue. Next, nother series of ANOVAs were conducted to look for men differences in totl BDI-II score nd the percentge contribution of the somtic-ffective fctor, loss of energy, chnges in sleeping ptterns, nd tiredness or ftigue items by whether or not ptients reported 1) ftigue s their worst MS symptom, 2) severe ftigue, or 3) excessive dytime sleepiness. These nlyses controlled for the potentilly confounding effects of ge, sex, eduction level, MS durtion, nd disbility sttus. Results Explortory Fctor Anlysis Explortory fctor nlysis reveled primry nd secondry fctor lodings very similr to those found by Beck et l. 7 (Tble 2). Only 3 of the 21 items loded differently in our smple. Two of the items, crying (item 10) nd gittion (item 11), were found by Beck et l. to cluster with the somtic-ffective items, while in our smple the two did not lod well on either of the fctors. The other item, indecisiveness (item 13), ws found by Beck et l. to lod primrily on the somtic-ffective fctor, even though it hd high secondry loding (0.34) on the cognitive fctor. We found this item to lod primrily, lbeit poorly (0.36), on the cognitive fctor, with lower secondry loding (0.21) on the somtic-ffective fctor. The three items ddressing ftigue (items 15, 16, nd 20) hd nerly identicl lodings compred with the results of Beck et l. Our results suggest tht the mesurement structure determined by Beck et l. 7 for the BDI-II is relible nd vlid in our smple of MS ptients. This is further indicted by the relibility (Cronbch α) vlues for Beck s scles in our smple, which were 0.83 for the somticffective items nd 0.84 for the cognitive items. Also, these scles pper to be vlid, s they both hve strong significnt correltion (Person r = 0.46) with ptient self-reported history of or current depression. Therefore, despite the few minor differences between our results nd those of Beck et l., we used the fctors nd corresponding items found by Beck et l. Men Percentge Contribution of BDI-II Items by Severity of Depression In our first series of ANOVAs by depression severity ctegory, we found tht the men percentge contribution to totl BDI-II score of the somtic-ffective fctor nd the three items tht ddress ftigue from this fctor (loss of energy, chnges in sleeping ptterns, nd tiredness or ftigue) significntly differed cross the four depression ctegories (Tble 3). In ech cse, the men percentge contribution to totl BDI-II score ws highest for those with miniml depression (score, 0 13), nd decresed in liner fshion s depression severity incresed. The results support the hypothesis tht inclusion of somtic items does not flsely elevte totl scores on the BDI-II. Men Percentge Contribution of BDI-II Items by Ftigue s Worst MS Symptom Respondents who reported ftigue s their worst MS symptom nd those who did not hd lmost identicl 170

5 Beck Depression Inventory nd MS Tble 2. Explortory fctor nlysis of BDI-II items BDI-II item (No. nd nme) Somtic-ffective fctor items MS smple (N = 557) Beck et l. 7 smple (N = 500) Somtic-ffective Cognitive Somtic-ffective Cognitive 20. Tiredness or ftigue Loss of energy Loss of interest Concentrtion difficulty Loss of plesure Chnges in sleeping ptterns Chnges in ppetite Loss of interest in sex Irritbility Cognitive fctor items 8. Self-criticlness Worthlessness Pst filure Guilty feelings Self-dislike Pessimism Punishment feelings Sdness Suicidl thoughts or wishes Indecisiveness Poorly loding items 10. Crying Agittion % Vrince explined by fctor Relibility (Cronbch α) Vlidity (correltion with self-reported history of or current depression) b 0.46 c 0.46 c Abbrevitions: BDI-II, Beck Depression Inventory II; MS, multiple sclerosis. Note: Vlues 0.35 pper in boldfce type. Totl % explined vrince: b Person r. c P <.001. men totl BDI-II scores (20.1 nd 20.9, respectively) (Tble 4). Among the three BDI-II items tht ddress ftigue, the men percentge contribution to the totl BDI-II score differed significntly between ptients who reported ftigue s their worst symptom nd those who did not only for the loss of energy item (9.5% vs. 7.6%). The men percentge contribution to the totl BDI-II score of the somtic-ffective fctor s whole did not differ significntly between these two groups of ptients. These results indicte tht higher BDI-II scores do not reflect greter contribution of somtic items even for individuls who identify ftigue s their worst MS symptom, lthough overlp could still be present. Men Percentge Contribution of BDI-II Items by Level of Ftigue nd Dytime Sleepiness The men totl BDI-II score ws significntly higher mong ptients with high level of ftigue (22.7 vs. 15.9) nd excessive dytime sleepiness (22.6 vs. 19.1). 171

6 Crwford nd Webster Tble 3. Men percentge contribution of BDI-II items to totl BDI-II score by depression severity ctegory (N = 557) Depression severity ctegory ccording to BDI-II score BDI-II fctor/item (1) 0 13 (miniml) (2) (mild) (3) (moderte) (4) (severe) Somtic-ffective fctor (F = 16.13),b (items 4, 10 13, 15 21) Loss of energy (F = 25.65),c Chnges in sleeping ptterns (F = 9.82),b Tiredness or ftigue (F = 5.59) d,e P <.001 cross depression severity ctegories. b Post hoc nlyses indicte sttisticlly significnt differences (P <.05) between miniml depression (ctegory 1) nd moderte (3) nd severe (4) depression, nd between mild (2) nd severe (4) depression. c Post hoc nlyses indicte sttisticlly significnt differences (P <.05) between miniml depression (ctegory 1) nd mild (2), moderte (3), nd severe (4) depression; nd between mild (2) nd miniml (1), moderte (3), nd severe (4) depression. d P <.01 cross depression severity ctegories. e Post hoc nlyses indicte sttisticlly significnt differences (P <.05) between miniml depression (ctegory 1) nd moderte (3) nd severe (4) depression. Tble 4. Men BDI-II totl score nd men percentge contribution to BDI-II score of ftigue items nd somtic-ffective fctor by whether ftigue is identified s worst symptom, ftigue level, nd sleepiness level Ftigue is worst MS symptom? (N = 557) FSS (N = 155) ESS (N = 155) Yes (n = 113, 20.3%) No (n = 444, 79.7%) F High ( 4) (n = 108, 69.7%) Low (<4) (n = 47, 30.3%) F High ( 10) (n = 67, 43.2%) Low (<10) (n = 88, 56.8%) F BDI-II totl score, men b Men % contribution to BDI-II score BDI-II items tht ddress ftigue (No. nd nme) 15. Loss of energy c Chnges in sleeping ptterns 20. Tiredness or ftigue Somtic-ffective fctor b (items 4, 10 13, 15 21) Abbrevitions: BDI-II, Beck Depression Inventory II; ESS, Epworth Sleepiness Scle; FSS, Ftigue Severity Scle; MS, multiple sclerosis. Note: All nlyses were controlled for ge, sex, eduction level, durtion of MS, nd disbility sttus. P <.001. b P <.05. c P <.01. Among the three items tht ddress ftigue nd the somtic-ffective fctor s whole, the men percentge contribution to totl BDI-II score differed significntly between ptients with severe ftigue nd those with norml levels only for the tiredness or ftigue item (7.5 vs. 4.4) nd the somtic-ffective fctor (66.2 vs. 60.8). There were no sttisticlly significnt differences on ny of the three items tht ddress ftigue nd the somticffective fctor s whole when compring ptients with nd without excessive dytime sleepiness. The higher BDI-II scores for ptients with severe ftigue nd excessive dytime sleepiness were not due to greter contri- 172

7 Beck Depression Inventory nd MS bution of somtic items, suggesting tht the contribution of items from the cognitive fctor contributed to the elevted scores. Conclusion Our findings indicte tht the BDI-II is vlid mesure for screening nd evluting depression in the MS popultion. Inclusion of somtic items on the BDI-II did not inflte totl scores even when ptients reported ftigue s their worst MS symptom or hd elevted levels of ftigue or dytime sleepiness. Cliniclly, it is not unusul for ptients to report feeling depressed s result of being too tired to engge in reltionships nd ctivities they previously enjoyed. Bsed on these results, we recommend tht ll items, including those tht ssess somtic symptoms, be included when using the BDI-II with individuls who hve MS. This sid, ptient reports on the BDI-II of ftigue or reduced energy could still reflect overlp with their neurologic symptoms. The full BDI-II cn lso be used to identify specific symptoms such s sleep onset nd mintennce difficulties tht contribute to ftigue nd could benefit from interventions, including eduction in sleep hygiene. Knowledge of sleep difficulties could led to the identifiction nd tretment of physicl symptoms such s nocturi nd spsticity tht interfere with sleep in ptients with MS. Dt from the BDI-II cn lso be used to help PrcticePoints Depression is common in people with MS nd is ssocited with significnt morbidity, including decresed dherence to MS tretment, decresed qulity of life, nd incresed risk of suicide. Despite the potentil overlp of somtic MS symptoms with symptoms of depression, the Beck Depression Inventory II (BDI-II) is vlid mesure for screening nd evluting depression in the MS popultion; inclusion of somtic items on the BDI-II does not significntly inflte totl scores, even in ptients who report ftigue s their worst MS symptom or elevted levels of ftigue or dytime sleepiness. The BDI-II is useful clinicl tool tht cn identify symptoms such s ftigue nd sleep difficulties tht cn be trgeted for tretment. It cn be completed periodiclly to monitor the effectiveness of tretment nd help provide feedbck to ptients on their progress. ptients nd their fmilies to understnd tht depression often presents with combintion of ffective, physicl, nd cognitive symptoms. Moreover, repeted ssessments using the full BDI-II during tretment for depression cn be used to provide feedbck to ptients bout chnges in their depression-relted symptoms, helping them monitor their progress. Implictions for Future Clinicl Reserch Although the present study focused on the men percentge contribution of somtic items to the overll BDI-II score, it would be interesting to exmine the contribution of other BDI-II items for exmple, those reflecting cognitive symptoms tht could overlp with symptoms of MS. Future studies testing the clinicl utility of the BDI-II with MS ptients would be useful. For exmple, it would be helpful to repet dministrtion of the BDI-II during tretment for depression t predetermined intervls nd ssess the ptient s response s form of feedbck. Repeted mesurements would lso llow for identifiction of differentil efficcy of tretment for exmple, which symptoms respond more quickly to tretment. This informtion could be provided to ptients before they strt tretment s wy of incresing their motivtion to follow through with mediction, psychotherpy, or both. o Finncil Disclosures: The uthors hve no conflicts of interest to disclose. References 1. Ptten SB, Beck CA, Willims JV, Brbui C, Metz LM. Mjor depression in multiple sclerosis: popultion-bsed perspective. Neurology. 2003:61: Mohr DC, Goodkin DE, Likosky W, Gtto N, Bumnn KA, Rudick RA. Tretment of depression improves dherence to interferon bet-1b therpy for multiple sclerosis. Arch Neurol. 1997;54: Sdovnick AD, Eisen K, Ebers GC, Pty DW. Cuse of deth in ptients ttending multiple sclerosis clinics. Neurology. 1991;41: Jønsson A, Dock J, Rvnborg MH. Qulity of life s mesure of rehbilittion outcome in ptients with multiple sclerosis. Act Neurol Scnd. 1996;93: Mohr DC, Goodkin DE, Likosky W, Beutler L, Gtto N, Lngn MK. Identifiction of Beck Depression Inventory items relted to multiple sclerosis. J Behv Med. 1997;20: Aikens JE, Reinecke MA, Pliskin NH, et l. Assessing depressive symptoms in multiple sclerosis: is it necessry to omit items from the originl Beck Depression Inventory? J Behv Med. 1999;22: Beck AT, Steer RA, Brown GK. Beck Depression Inventory II Mnul. Sn Antonio, TX: Psychologicl Corportion; Krupp LB, LRocc NG, Muir-Nsh J, Steinberg AD. The ftigue severity scle: ppliction to ptients with multiple sclerosis nd systemic lupus erythemtosus. Arch Neurol. 1989;46: Johns MW. A new method for mesuring dytime sleepiness: the Epworth sleepiness scle. Sleep. 1991;14: