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A new clinical rating scale for work absence and productivity: validation in patients with major depressive… Lam, Raymond W; Michalak, Erin E; Yatham, Lakshmi N Dec 3, 2009

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ralssBioMed CentBMC PsychiatryOpen AcceResearch articleA new clinical rating scale for work absence and productivity: validation in patients with major depressive disorderRaymond W Lam*, Erin E Michalak and Lakshmi N YathamAddress: Department of Psychiatry; University of BC; Mood Disorders Centre, UBC Hospital, Vancouver, CanadaEmail: Raymond W Lam* - r.lam@ubc.ca; Erin E Michalak - emichala@interchange.ubc.ca; Lakshmi N Yatham - yatham@exchange.ubc.ca* Corresponding author    AbstractBackground: The prevalence of major depressive disorder (MDD) is highest in working agepeople and depression causes significant impairment in occupational functioning. Workproductivity and work absence should be incorporated into clinical assessments but currentlyavailable scales may not be optimized for clinical use. This study seeks to validate the LamEmployment Absence and Productivity Scale (LEAPS), a 10-item self-report questionnaire thattakes 3-5 minutes to complete.Methods: The study sample consisted of consecutive patients attending a Mood Disordersoutpatient clinic who were in full- or part-time paid work. All patients met DSM-IV criteria forMDD and completed during their intake assessment the LEAPS, the self-rated version of the QuickInventory for Depressive Symptomatology (QIDS-SR), the Sheehan Disability Scale (SDS) and theHealth and Work Performance Questionnaire (HPQ). Standard psychometric analyses forvalidation were conducted.Results: A total of 234 patients with MDD completed the assessments. The LEAPS displayedexcellent internal consistency as assessed by Cronbach's alpha of 0.89. External validity wasassessed by comparing the LEAPS to the other clinical and work functioning scales. The LEAPS totalscore was significantly correlated with the SDS work disability score (r = 0.63, p < 0.01) and theGlobal Work Performance rating from the HPQ (r = -0.79, p < 0.01). The LEAPS total score alsoincreased with greater depression severity.Conclusion: The LEAPS displays good internal and external validity in a population of patients withMDD attending an outpatient clinic, which suggests that it may be a clinically useful tool to assessand monitor work functioning and productivity in depressed patients.BackgroundMental illnesses in general, and major depressive disorder(MDD) in particular, are among the most common, disa-bling and costly of medical conditions. The total eco-[1], US$83 billion in the United States [2], and €118 bil-lion in Europe [3].The prevalence of MDD in the general population is high-Published: 3 December 2009BMC Psychiatry 2009, 9:78 doi:10.1186/1471-244X-9-78Received: 2 September 2009Accepted: 3 December 2009This article is available from: http://www.biomedcentral.com/1471-244X/9/78© 2009 Lam et al; licensee BioMed Central Ltd. This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/2.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.Page 1 of 7(page number not for citation purposes)nomic burden (both direct and indirect costs) ofdepression were estimated at over C$6 billion in Canadaest in those of typical working age (15-64 years) [4] and,given the nature of the physical and cognitive symptomsBMC Psychiatry 2009, 9:78 http://www.biomedcentral.com/1471-244X/9/78of depression, it is not surprising that the major portion ofthe economic burden of MDD arises from impairment inoccupational functioning. Numerous studies have docu-mented that clinical depression is associated with highrates of absenteeism, or time away from work. For exam-ple, depressed workers in the United States reported 1.5-3.2 more short-term work-disability days per month,compared to people who were not depressed [5], while aCanadian study found that approximately 2.5% ofemployees in 3 large companies had at least 1 depression-related short-term disability leave [6]. Similarly, in theEuropean ESEMeD study, depressed workers had 3-4times more work-loss days per month than those withoutdepression [7].While the economic costs of depression-related absentee-ism are significant, they are dwarfed by those attributed topresenteeism, in which depressed workers stay at work buthave reduced productivity as a result of their condition. Ina community survey in Canada, 29% of people with a his-tory of MDD in the past year reported reduced activities atwork, compared to only 10% of people with no history ofdepression [8]. Almost half of people with chronic depres-sion reported reduced productivity at work [9] and thecosts of productivity losses associated with MDD havebeen estimated in the United States (in 2002) at overUS$31 billion [10].Given the magnitude of occupational impairment inMDD, it is important to include assessment of work func-tioning within the clinical evaluation and management ofthe condition. There are many validated scales used tomeasure work performance and productivity, includinggeneric productivity scales (e.g., Work Limitations Ques-tionnaire [11], Stanford Presenteeism Scale [12]) that areuseful for comparisons with other disease conditions.However, there are few work performance scales designedspecifically for use in a depressed population. A rationalefor using disease-specific measures includes the potentialfor such scales to provide more specific information thatmight otherwise be missed or to be more sensitive tochange than generic counterparts [13]. For example, adepression-specific scale for work functioning may proveuseful as a clinical tool for monitoring progress duringtreatment and/or as an outcome measure in clinical trialsfor MDD. This study seeks to validate a new clinical ratingscale for work functioning and productivity in patientswith MDD.MethodsScale DevelopmentThe Lam Employment Absence and Productivity Scale(LEAPS) was designed to assess work functioning andthe literature on depressive symptoms and interferencewith work functioning, and on the common work-relatedproblems experienced by people with depression.The LEAPS (Additional file 1) is a self-rated questionnaireconsisting of 10 items: the first item asks the respondentto list their occupation and the next two items ask aboutthe number of work hours scheduled in the past twoweeks and the number of work hours missed. These itemsassess absenteeism, which can be expressed as a propor-tion (%) of work hours scheduled. Finally, there are 7items rated on a 5-point Likert scale with the followingresponse format: 'None of the time (0%)', 'Some of thetime (25%)', 'Half the time (50%)', 'Most of the time(75%)', 'All the time (100%)', scored as 0-4, respectively.The LEAPS total score therefore ranges from 0 to 28. A"productivity subscale" sums the scores from the 3 itemsassessing work functioning and productivity (doing lesswork, doing poor quality work, and making more mis-takes).Subjects and ProceduresThe validation sample consisted of consecutive patientswith MDD attending a Mood Disorders clinic at a univer-sity teaching hospital. Patients were referred from primarycare physicians and from community psychiatrists. Clini-cal assessments were conducted by board-certified psychi-atrists. Diagnoses were assigned according to DSM-IVcriteria based on clinical interviews supplemented by asymptom check list and all available medical information.Inclusion criteria for this study included a DSM-IV diag-nosis of MDD; patients with bipolar disorder wereexcluded. Patients also had to be working, defined as paidwork (employed or self-employed), either part-time orfull-time. Patients on short-term or long-term work disa-bility were excluded. This study was approved by the Clin-ical Research Ethics Board of the University of BritishColumbia.Patients completed several questionnaires at initial assess-ment, including the Quick Inventory of Depressive Symp-tomatology, Self-Rated (QIDS-SR), a validated and widelyused self-rated scale to assess severity and type of depres-sive symptoms [14]. In addition, subjects completed theHealth and Work Performance Questionnaire (HPQ,[15]) and the Sheehan Disability Scale (SDS, [16]). TheHPQ was developed for the World Health Organization asa depression-specific, self-rated questionnaire thatassesses illness-related work absence (as number of hours/week), work productivity, Global Work Performance, andjob-related accidents. The HPQ has been validated againstobjective measures of absence and performance in anumber of blue-collar and white-collar occupationsPage 2 of 7(page number not for citation purposes)impairment in a clinically depressed population. Theitems were constructed and selected based on a review of[17,18] and can be considered the "gold standard" pro-ductivity assessment. The SDS is a generic self-reportBMC Psychiatry 2009, 9:78 http://www.biomedcentral.com/1471-244X/9/78inventory that assesses the degree to which symptomshave disrupted the person's work, social life, and familylife. A single question assesses work/school impairment,formatted as 'The symptoms have disrupted your work/school work:' and rated on a 0-10 point scale ranging from'Not at all (0)' through 'Mildly (1-3)', 'Moderately (4-6)'and 'Markedly (7-9)' to 'Extremely (10)'. There are twoadditional items which inquire about the number of dayslost in the past month owing to absence or reduced pro-ductivity.Statistical ProceduresAll results are reported as means ± standard deviations(SD). Construct validation of a scale for work functioningis complex because there are no definitive measures forthe underlying construct. Hence, we conducted a series ofscale validation procedures. Internal consistency (thedegree to which the items of a scale measure the same con-struct) of the 7 LEAPS items was measured using Cron-bach's alpha. To assess the structure of the LEAPS, a factoranalysis was conducted using Principal Components Anal-ysis with varimax rotation. Convergent validity is the degreeof correlation between a new scale and previously vali-dated measures of the same construct. This was assessedusing two-tailed Pearson correlations between the LEAPStotal score and scores on other scales measuring work pro-ductivity. In addition, work functioning would beexpected to be more impaired as the depressive symp-tomatology worsens. Therefore, the LEAPS should discrim-inate between severity categories (e.g., minimallydepressed versus more severely depressed) of depression.This was evaluated by examining mean scores on theLEAPS across the range of severity categories of the QIDS-SR, using one-way ANOVA. If the overall F was significant,post hoc pairwise comparisons between severity catego-ries were examined using Tukey's HSD to control for mul-tiple comparisons. All statistical analyses were conductedusing SPSS, V.16 [19].ResultsSubject Demographic VariablesTable 1 shows the demographic and clinical informationfor the 234 subjects studied. The profile is typical of amood disorders cohort attending a specialty clinic. Themean score on the QIDS-SR was 13.8 ± 5.9, indicating amoderate severity of depression. The subjects missed anaverage of 10 hours of work in the past 2 weeks owing totheir symptoms, which represented 16% of the time theywere scheduled to work.Internal ConsistencyThe Cronbach's alpha for the 7 Likert-scored items on theLEAPS was 0.89, indicating that the LEAPS items showedhigh internal consistency.Factor AnalysisTable 2 shows the results of the factor analysis with var-imax rotation conducted on the 7 Likert-scored items ofthe LEAPS. Two factors were identified on the PrincipalComponents Analysis that accounted for 75% of the vari-ance in the LEAPS total score. The first factor included the3 items relating to work productivity, which accounted for60% of the variance. The second factor comprised the 4items relating to troublesome symptoms, whichaccounted for an additional 15% of the variance.Convergent ValidityTable 3 shows the Pearson correlation matrix for theLEAPS total score and the productivity subscale score withother work functioning and productivity measures. ThereTable 1: Demographic and clinical features of the validation sample (N = 234).Variable Mean ± SDAge (years) 39.2 ± 11.7Marital status (% of sample) (married/single/divorced/separated) 43/34/14/9Number of episodes 2.5 ± 4.3Duration of current episode (months) 6.9 ± 8.9QIDS-SR score 13.8 ± 5.9Number of hours in the past 2 weeks scheduled or expected to work 60.3 ± 22.4Number of hours in the past 2 weeks missed from work 10.2 ± 17.8% of work hours missed (per hours scheduled) 16.2% ± 27.0%Page 3 of 7(page number not for citation purposes)SD, standard deviation; QIDS-SR, Quick Inventory of Depressive Symptomatology, Self-Rated.BMC Psychiatry 2009, 9:78 http://www.biomedcentral.com/1471-244X/9/78were significant correlations between the scores with allthe other measures, including a high correlation with the"gold standard" HPQ Global Work Performance rating.Only a moderate correlation was found with the SDSWork score, likely explained by the fact the SDS score iscomprised of a single item. The LEAPS total score andwork productivity subscale score also explained more ofthe variance with '% hours of work missed' than either theSDS Work score (r = 0.24) or the HPQ Global Work Per-formance score (r = -0.37).Discrimination Between Depression Severity CategoriesTable 4 shows the mean scores on the LEAPS for each ofthe severity categories of the QIDS-SR depressive symp-tom scale. There were significant differences in the LEAPStotal scores overall (one-way ANOVA: F = 47.4, df = 4,229,p < 0.01). Post hoc Tukey's HSD tests showed significantdifferences (p < 0.05) between each pairwise comparison,except between the Severe and Very Severe categories. Sim-ilar results were seen with the LEAPS productivity subscalescores.Figure 1 shows the degree of clinical impairment (definedas percentage of the sample scoring 2 or higher on theitem, indicating 50% or more of the time) in the individ-ual productivity items associated with depression severitycategories (as defined by the QIDS-SR scores).DiscussionThe results from this validation study suggest that the psy-chometric properties of the LEAPS are very good. TheLEAPS demonstrated a high internal consistency as meas-ured by Cronbach's alpha. The factor analysis of theLEAPS showed that it is comprised of two factors, termedWork Productivity and Troublesome Symptoms, whichaccount for a large proportion of the variance in totalscores.The validity of the LEAPS was further supported by the sig-nificant correlations with other validated measures ofwork functioning and productivity, including the SDS andthe HPQ. Only a moderate correlation (explaining 40% ofthe variance) between the LEAPS and the SDS wasobserved, which is to be expected given that the SDS Workscore is comprised of only a single item, compared to thehigher correlation (explaining over 60% of the variance)found with the HPQ. The LEAPS score also showed highercorrelations with the '% of work hours missed' over a 2-Table 2: Factor loadings of the 7 items on the LEAPS (Principal Components Analysis, using varimax rotation).LEAPS Item Factor 1 (Work productivity) Factor 2 (Troublesome Symptoms)Low energy or motivation 0.40 0.72Poor concentration or memory 0.28 0.78Anxiety or irritability 0.23 0.82Getting less work done 0.73 0.46Doing poor quality work 0.85 0.31Making more mistakes 0.90 0.10Having trouble getting along with people, or avoiding them 0.15 0.86LEAPS, Lam Employment Absence and Productivity Scale.Table 3: Pearson correlations of LEAPS scores with other work functioning and productivity measures.LEAPS score SDS-Work HPQ Global Work PerformanceHPQ Productivity (4 items)% of work hours missed in the past 2 weeksTotal Score* 0.63 -0.79 -0.70 0.41Work productivity subscale (3 items) score*0.50 -0.85 -0.77 0.45LEAPS, Lam Employment Absence and Productivity Scale; SDS-Work, Sheehan Disability Scale, Work item; HPQ, Health and Work Performance Page 4 of 7(page number not for citation purposes)Questionnaire.*All correlations are significant at p < 0.01.BMC Psychiatry 2009, 9:78 http://www.biomedcentral.com/1471-244X/9/78week period than the SDS Work score and the HPQ Glo-bal Work Performance rating.The LEAPS scores also increase significantly with increas-ing overall severity of depressive symptoms and can dis-criminate between various depression severity categories,such as between 'None to minimal' and more severelydepressed categories. The results from the individual pro-ductivity items on the LEAPS indicate that significantwork impairment is found in patients with MDD. Morethan 75% of patients with higher severity of depressivesymptoms described problems "much of the time" or "allthe time" with the quantity and quality of work. In addi-tion to productivity loss, the LEAPS data show thatdepressed patients were absent from work for 16% of theirscheduled work hours (over 1.5 typical working days) inthe previous two weeks. This is of similar magnitude tofindings from other studies of work absence [5,7] andillustrates the substantial impact of depression on absen-teeism.Although the LEAPS performs well in this population, thelimitations of this study need to be acknowledged. Furtherstudies are needed to validate the LEAPS against externaland objective measures of work performance, such asemployer work absence data and objective measures ofproductivity. However, other studies have shown that self-rated work productivity measures are significantly corre-lated with objective metrics [20,21] and with administra-tive work records [15]. In addition, further studies arerequired to investigate the performance of the LEAPS innon-clinical samples of workers and in other clinical pop-ulations in specialist and primary care settings.Clinical treatment studies in MDD now focus on symp-tom remission because of the evidence for poor outcomespredicted by the presence of residual depressive symp-toms [22]. However, functional improvement, includingthat of work functioning, is more relevant to patients andrestoration of occupational functioning is important tosociety [23]. The concept of measurement-based care fordepression [24], in which outcomes are assessed usingvalidated scales and which is increasingly recommendedby clinical guidelines for the management of MDD [25],should encompass work functioning as well as symptomseverity.Many of the validated scales that assess work functioningare "generic" in that they are designed to evaluate produc-tivity across a wide range of non-specific medical condi-tions. Alternatively, a disease-specific scale can provideimportant information for a defined clinical population.There are few depression-specific productivity scales avail-able. The HPQ is the "gold standard" scale for assessmentof work performance in patients with depression, but at37 items and 8 pages in length, the respondent burdenmay be too high for routine clinical use. In contrast, theLEAPS is short (10 items on a single page) and simple andtakes only 3-5 minutes to complete. Its brevity suggeststhat it will be an efficient tool for use in clinical settings.For example, the LEAPS can be used alongside symptomscales to monitor treatment progress, to ensure that workfunctioning improves in parallel with clinical symptoms.Additionally, scores on individual items (e.g., makingmistakes) can be used to inform discussions withdepressed workers regarding whether to stay at work ortake time off while being treated for MDD.Table 4: Mean scores on the LEAPS total and Productivity Subscale versus depression severity (based on QIDS-SR score).QIDS-SR Severity Category (score range) N LEAPS total score* SD LEAPS Productivity Subscale score* SDNone to minimal (0-5) 25 2.6 2.3 0.6 0.9Mild (6-10) 41 8.4 4.6 2.9 2.1Moderate (11-15) 78 13.1 4.6 4.8 2.7Severe (16-20) 57 15.7 5.7 6.6 3.2Very Severe (21-27) 33 18.2 6.7 5.9 4.4Total 234 12.5 6.8 4.6 3.4QIDS-SR, Quick Inventory of Depressive Symptomatology, Self-Rated; LEAPS, Lam Employment Absence and Productivity Scale; SD, standard deviation.* p < 0.05, one-way ANOVA using post hoc Tukey's Highly Significant Differences for all pairwise comparisons, except between Severe and Very Severe categories.Page 5 of 7(page number not for citation purposes)BMC Psychiatry 2009, 9:78 http://www.biomedcentral.com/1471-244X/9/78The productivity impairment measured by the LEAPSincreases, as expected, with increasing severity of depres-sion. Although this is a cross-sectional observation, it sug-gests that the scale may also be useful as an outcomemeasure for occupational functioning in clinical trials ofMDD. Further studies are underway to investigate the util-ity of the LEAPS to assess change in work functioning withtreatment of MDD.ConclusionThe LEAPS is a short and simple self-rated scale of workabsence and productivity that has been designed for use ina clinically depressed population. It displays good inter-nal and external validity compared to other validated, self-rated scales of work performance and productivity. Fur-ther studies will be needed to determine whether theLEAPS can be used in other populations or as an outcomemeasure for clinical trials, and whether it will prove usefulas a clinical tool to assess and monitor occupational func-tioning in patients with MDD.Competing interestsRWL has received honoraria for consulting/speakingfrom: Advanced Neuromodulation Systems Inc., Astra-Zeneca, Biovail, Canadian Network for Mood and AnxietyTreatments, Eli Lilly, Janssen, Litebook Company Ltd.,Lundbeck, Lundbeck Institute, Servier, Takeda, andPsychiatric Research Foundation, Litebook Company Ltd.,Lundbeck, Mathematics of Information Technology andAdvanced Computing Systems, Michael Smith Founda-tion for Health Research, Servier, and UBC Institute ofMental Health/Coast Capital Savings. He holds a copy-right on the LEAPS.EEM declares that she has no competing interests.LNY has received honoraria for consulting/speaking from:AstraZeneca, Bristol Myers Squibb, Canadian Network forMood and Anxiety Treatments, GlaxoSmithKline, Janssen,Pfizer, Ranbaxy, and Scherring Plough. He has receivedresearch grants from: AstraZeneca, Bristol Myers Squibb,Canadian Institutes of Health Research, Janssen, MichaelSmith Foundation for Health Research, Servier, andStanley Foundation.Authors' contributionsRWL conceived the study, designed the scale, contributedto data acquisition, conducted the statistical analysis,interpreted the data, wrote the initial draft of the manu-script, and funded the study through internal researchfunds. EEM contributed to study design and data acquisi-tion, interpreted the data, and revised drafts of the manu-script. LNY contributed to study design and dataacquisition, interpreted the data, and revised drafts of theSignificant impairment in work productivity items (from the LEAPS) versus depression severity (based on QIDS-SR score)Figure 1Significant impairment in work productivity items (from the LEAPS) versus depression severity (based on QIDS-SR score).Percentage of sample endorsing 50% or more of the time…Doing poor quality workMaking more mistakesGetting less work doneModerately depressed (N=78)Severely depressed (N=57)Very Severely depressed (N=33)LEAPS Work Productivity ItemsMildly depressed (N=41)Minimally depressed (N=25)Page 6 of 7(page number not for citation purposes)Wyeth. He has received research grants from: AdvancedNeuromodulation Systems Inc., AstraZeneca, BrainCellsInc., Canadian Institutes of Health Research, Canadianmanuscript. All authors read and approved the final man-uscript.Publish with BioMed Central   and  every scientist can read your work free of charge"BioMed Central will be the most significant development for disseminating the results of biomedical research in our lifetime."Sir Paul Nurse, Cancer Research UKYour research papers will be:available free of charge to the entire biomedical communitypeer reviewed and published immediately upon acceptancecited in PubMed and archived on PubMed Central BMC Psychiatry 2009, 9:78 http://www.biomedcentral.com/1471-244X/9/78Additional materialAcknowledgementsThe authors would like to acknowledge their appreciation to the patients attending the Mood Disorders Centre, UBC Hospital, for their participa-tion in this study. Erin Michalak is supported by a Michael Smith Scholar Award from the Michael Smith Foundation for Health Research and a New Investigator Award from the Canadian Institutes for Health Research.References1. 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Am J Psychi-atry 2006, 163:28-40.25. Lam RW, Kennedy SH, Grigoriadis S, McIntyre RS, Milev R, Ramas-ubbu R, Parikh SV, Patten SB, Ravindran AV: Canadian Networkfor Mood and Anxiety Treatments (CANMAT) clinicalguidelines for the management of major depressive disorderin adults. III. Pharmacotherapy.  J Affect Disord 2009, 117(Suppl1):S26-S43.Pre-publication historyThe pre-publication history for this paper can be accessedhere:http://www.biomedcentral.com/1471-244X/9/78/prepubAdditional file 1The LEAPS. The self-rated questionnaire consisting of 10 items that was used in the study.Click here for file[http://www.biomedcentral.com/content/supplementary/1471-244X-9-78-S1.PDF]yours — you keep the copyrightSubmit your manuscript here:http://www.biomedcentral.com/info/publishing_adv.aspBioMedcentralPage 7 of 7(page number not for citation purposes)report (QIDS-SR): a psychometric evaluation in patientswith chronic major depression.  Biol Psychiatry 2003, 54:573-583.

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