Screening for Distress and Depression in Cancer Patients: Is Ultrashort Depression Screening a Valid Measure in the UK? A Prospective Validation Study

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1 234 Journal of Pain and Symptom Management Vol. 38 No. 2 August 2009 Original Article Screening for Distress and Depression in Cancer Patients: Is Ultrashort Depression Screening a Valid Measure in the UK? A Prospective Validation Study Joseph Low, PhD, MSc, BSc, Sue Gessler, AFBPsS, PhD, MSc, BA, Rachael Williams, MSc, BSc, Emma Daniells, MSc, BSc, Veronica Brough, BSc, Adrian Tookman, MB, FRCP, and Louise Jones, MBBS Department of Mental Health Sciences (J.L., R.W., E.D., V.B., A.T., L.J.), Marie Curie Palliative Care Research Unit, Royal Free & University College Medical School; and UCL Hospitals Gynaecological Oncology Centre (S.G.), Elizabeth Garrett Anderson Hospital, London, United Kingdom Abstract This study sought to validate the two-question (2Q) depression screen as a screening tool for psychological distress and depression against four criterion measures (Hospital Anxiety and Depression Scale [HADS], General Health Questionnaire-12, Brief Symptom Inventory-18 [BSI-18], and the distress thermometer) for a UK cancer population. We used a prospective cross-sectional study design. A consecutive sample of 399 outpatients from four outpatient oncology clinics and a palliative care day center in North London were initially identified. Of these, 249 were eligible, of whom 171 consented to take part. Data were analyzed using receiver operating characteristic analysis to examine the sensitivity and specificity of the 2Q depression instrument against the cutoff scores already shown to demonstrate clinically significant symptoms ( caseness ) in the criterion measures. Sensitivity and specificity, with 95% confidence intervals, were calculated in addition to positive and negative predictive values. The 2Q depression screen showed sensitivity of 68%e89% and specificity of 70%e84% when compared with our four criterion measures in screening for psychological distress; its best performance was against the HADS (89% sensitivity and 79% specificity). In screening for depression, the 2Q depression screen showed sensitivity of 84%e94% and specificity of 72%e73% when compared with our two criterion measures, its best performance being against the BSI depression subscale (94% sensitivity and 72% specificity). Our study demonstrated that the 2Q depression screen showed good psychometric properties, which further supports its usefulness as a simple instrument in screening for psychological distress in cancer patients in the UK. J Pain Symptom Manage 2009;38:234e243. Ó 2009 U.S. Cancer Pain Relief Committee. Published by Elsevier Inc. All rights reserved. This study was funded by Marie Curie Cancer Care. Address correspondence to: Joseph Low, PhD, Department of Mental Health Sciences, Marie Curie Palliative Care Research Unit, Royal Free & University Ó 2009 U.S. Cancer Pain Relief Committee Published by Elsevier Inc. All rights reserved. College Medical School, Rowland Hill Street, London NW3 2PF, United Kingdom. j.low@ medsch.ucl.ac.uk Accepted for publication: August 8, /09/$esee front matter doi: /j.jpainsymman

2 Vol. 38 No. 2 August 2009 UK Validation of a 2Q Depression Screen 235 Key Words Sensitivity, specificity, receiver operating characteristic analysis, cancer, psychological distress Introduction Clinically significant distress in cancer patients, including depression and anxiety, has been recognized for over 20 years, 1 and is experienced by up to 50% of these patients during some point in their cancer journey. 2 Prompt intervention can improve treatment adherence and reduce medical costs by 25%, 3 and information regarding distress improves both medical and emotional aspects of consultations. 4 Distress was initially described using measures standardized for psychiatric disorders. 5,6 These require training to administer and score; patients may require help to complete them 7 and may reject their use. 8 In addition, their use among cancer patients has been criticized as being both insensitive and obtrusive. 9e11 A measure is needed to help staff respond to common reactions to a life-threatening diagnosis and its treatment while screening for more serious, treatable conditions, such as depression. This has led to a growing interest in the use of ultrashort screening methods, consisting of less than five items and delivered either orally or in a written format, for detecting cancer-related mood disorders. 12 One approach increasingly used by clinicians in primary care involves asking patients either one question, During the past month, have you often been bothered by feeling down, depressed or hopeless? (one-question [1Q] depression screen), or two questions, with the second being, During the past month, have you often been bothered by little interest or pleasure in doing things? (two-question [2Q] depression screen). 13 Such approaches have been recommended by The National Institute for Clinical Excellence (NICE) for use in primary care. 14 These questions are derived from the major depression module of the Structured Clinical Interview for DSM-IIIR (Diagnostic and Statistical Manual of Mental Disorders, 3rd Edition), and a recent meta-analysis has indicated that, in primary care, these ultrashort screening instruments were accurate in excluding a diagnosis of depression, but less so in detecting it. 15 Within a cancer setting, most researches have focused on patients with terminal or palliative care needs, and it has not been possible to generalize the findings from the 2Q depression screen to the wider cancer population. Although the 2Q depression screen has been shown to demonstrate high sensitivity and specificity values against a semistructured diagnostic psychiatric interview, 16e19 no studies have been conducted to rate its performance against other standardized instruments. We report the performance of the ultrashort 2Q depression screen in its ability to screen for both psychological distress and depression in a diverse cancer population against four measures commonly used in the physically ill population and the cancer population. This study was conducted as part of work to validate the distress thermometer (DT) for use in the United Kingdom. 20 Methods Ethical Approval Ethical approval was granted by the Joint University College London/University College London Hospital (UCL/UCLH) Committees on the Ethics of Human Research (Committee A; Ref no. 05/Q0505/55). In addition, the study was reviewed by the Marie Curie Palliative Care Research Unit and the Royal Free Hospital Oncology Consumer Group. Sample As the main aim of our study was to show that the 2Q depression screen was applicable and relevant to all users in a cancer service, in line with the recommendations set by the UK NICE guidance, 21 we chose outpatient clinics that reflected a wide range of patients with cancer in terms of gender and age. A palliative care sample was obtained to ensure that we had representation in this phase of illness. Hence, participants were recruited from outpatient clinics at the Royal Free Hospital (melanomarenal and gastrointestinal oncology), at University College London Hospitals (gynecological

3 236 Low et al. Vol. 38 No. 2 August 2009 oncology and gastrointestinal), and outpatient services at the Day Therapy Unit, Marie Curie Hospice, Hampstead, between October 2005 and June All outpatients were initially eligible to participate, regardless of the stage of the disease; hence, a consecutive sample was used. Patients were excluded from initial approach by the researcher if they were new patients who might not have received a cancer diagnosis, were considered by their doctor to be clinically inappropriate for the study, were under 18 years of age, were suffering from organic brain disease or psychotic illness, or were unable to understand written English. Participant Recruitment The eligible patients were identified by their doctor or nurse who asked for initial consent. Patients in oncology clinics were then approached with written information about the study, and those who gave informed consent were asked to complete the questionnaires. Outpatients attending the Day Therapy Unit were sent information by post. Patients who refused were not approached again. Sample Size Calculation The original sample size calculation showed that a sample of 293 patients was required to achieve a 95% confidence interval of around the assumed optimal cutoff point of 1 on the 2Q depression screen, where both the sensitivity and the specificity values are equal to Test Methods Reference Standards. The reference standards for the study were four widely used screening questionnaires standardized for use with physically ill patients: Hospital Anxiety and Depression Scale (HADS): 5 The HADS is a 14-item measure which gives scores for possible and probable anxiety and depression. When a global score is used, a case for emotional distress is defined as a score of 15 or more. If the depression subscale consisting of seven items (HADS-D) is used, a case is defined as a score 7 or more. General Health Questionnaire-12 (GHQ- 12): 6 The GHQ-12 is a 12-item measure used to detect psychological morbidity. A score of 4 or more is indicative of a possible case in psychological strain. Brief Symptom Inventory-18 (BSI-18). 22 The BSI-18 is an 18-item measure to detect psychological distress and psychiatric morbidity, which yields a composite score (Global Severity Index) or a depression subscale of six items (BSI-D), where a case on both is defined as a t-score $ 63. DT 20,23 : DT is a one-item measure to detect psychological distress. It is laid out in a thermometer-style format, and scored on a scale of 0e10. It has recently been validated in a UK cancer population, in which a score of 5 or more is defined as a case of psychological distress. It is further accompanied by a checklist of 38 items divided into five subcategories to help clinicians identify the source of psychological distress for patients. For this study, this section was not used for analysis purposes. Although all the aforementioned measures have been validated for general medical populations, there is some debate regarding their appropriateness in palliative care. Some studies reject the use of the HADS for this population because of low sensitivity obtained, 10 although others suggest that both the global HADS score and GHQ-12 can be used. 24 For our test measure, we used the 2Q depression screen, which incorporates the following two questions: During the past month, have you often been bothered by feeling down, depressed or hopeless? (1Q depression screen), and During the past month, have you often been bothered by little interest or pleasure in doing things? (1Q anhedonia), 13 to which a respondent gives either a yes or a no answer. A positive case is one in which a person responds as yes to one or both questions. 13,17 Both questions can be treated as separate items, in which instance, a yes response to either question represents a case for that particular question. As there is currently no gold standard measure of distress among palliative care patients, this study measures the performance of the 2Q depression screen against those reference standards most commonly used. In addition, we include the DT as an alternative ultrashort screening tool, which is currently

4 Vol. 38 No. 2 August 2009 UK Validation of a 2Q Depression Screen 237 widely used in cancer and palliative care populations. We compiled the 2Q depression screen, together with our four standard references, into a battery of questionnaires that patients were given to self-complete. Procedure Patients who gave formal consent completed the questionnaires either in clinic or at home. All measures were administered at the same time. The researchers collected and scored them and input the data with the assistance of the statistician. The researchers were initially trained and subsequently supervised through the study by a clinical psychologist and a health psychologist. Because as all measures were completed at the same time, it was not possible to blind researchers to the test results. For ethical reasons, patients who expressed suicidal ideation or whose scores on any of the reference tests were a cause for concern were discussed with a senior clinician in the research team and appropriate action was taken. Statistical Methods Data were analyzed using Stata version 9.1 (StataCorp LP, College Station, TX). Frequencies and percentages, means, and standard deviations were used to describe participants demographic details. Receiver operating characteristic analysis was used to examine the sensitivity and specificity of the 2Q depression screen and its individual items against the cutoff scores already shown to demonstrate clinically significant symptoms ( caseness ) in the criterion measures. Analysis was restricted to those patients who completed the 2Q depression screen and at least one reference standard. Sensitivity and specificity, with 95% confidence intervals, were calculated, in addition to positive predictive values (PPVs), negative predictive values (NPVs), false-positive rate (FPR), and false-negative rate (FNR). Sensitivity values, specificity values, PPV, and NPV of 70% or above were considered acceptable, and values of 80% or above were considered high. FPR and FNR of 30% or lower were considered low. In addition, subgroup analysis was conducted on patients from the oncology clinics, though not on patients from the palliative care clinics, as the sample size from this group was small (n ¼ 11). Results Recruitment and Follow-up Of the 399 screened patients who attended the clinics between October 2005 and June 2006, 54 were identified as ineligible by the health care professional, 71 patients were not approached because they were new to the clinic, and 25 patients did not have sufficient knowledge of English to participate. The remaining 249 (62%) patients were approached by a health care professional to take part in the study. Of these, 171 participated, 22 refused, and 56 did not return the baseline questionnaire, giving an overall response rate of 69% (Fig. 1). Identified possible participants 399 New referrals 75 Identified as too ill 54 Insufficient English 25 Eligible patients 249 Completed baseline questionnaire 171 Did not complete baseline questionnaire 78 Fig. 1. Details of recruitment.

5 238 Low et al. Vol. 38 No. 2 August 2009 Participants were found to be similar to eligible nonparticipants both in terms of gender (53% female compared with 50% female (X 2 (1, n ¼ 249) ¼ 0.15, P ¼ 0.700)) and age (mean age of 60 years compared with 61 [t ¼ 0.716, P ¼ 0.475]). Participants The 171 participants were recruited from the following clinics: 106 from gastrointestinal oncology, 32 from melanoma-renal oncology, 22 from gynecological oncology, and 11 from specialist palliative care. Table 1 shows that the sample was evenly split for gender (males: 47%), with a mean age of 60 years. Participants were predominantly white (86%), with half being married or living with a partner (63%). Most had achieved a qualification of some level (76%), came mainly from managerial, professional, or intermediate occupations (63%), and owned their own home (71%), although a large proportion were retired or on sick leave at the time of the study (48%). Using Chisquared and Fisher s exact tests, no significant differences were found between the clinic samples other than gender. As the number of participants (171) was smaller than the calculated sample size (293) for testing concurrent validity, retrospective power calculations were used. These showed that with a sample size of 171, a 95% confidence interval of could be achieved at a cutoff point, where the sensitivity and the specificity values were equal to The results show that, although the number of participants was smaller than anticipated, the estimated confidence intervals were comparable to those used in the original sample size calculations. Screening for Psychological Distress Using the Two-Question Depression Screen The 2Q depression screen was found to perform well against GHQ-12, with acceptable sensitivity and high specificity, PPV, and NPV (Table 2). High sensitivity and NPV and acceptable specificity were shown against the HADS and BSI-18, although PPV against these measures was lower. The sensitivity of the 2Q depression screen against the DT was not considered acceptable. Analysis of the results from only the oncology patients showed the same aforementioned pattern. Screening for Psychological Distress Using the One-Question Depression Screen The single depression item performed less well against each of the criterion measures (Table 3). Against the HADS, sensitivity, specificity, and NPV were high, although PPV was lower. Against the BSI-18, sensitivity and NPV were high, and specificity was acceptable, although PPV was again lower. Sensitivity of the depression item against the GHQ-12 and the DT was not considered acceptable. Analysis of the results from only the oncology patients showed the same aforementioned pattern. Screening for Psychological Distress Using the One-Question Anhedonia Screen The question assessing anhedonia looks at lack of experienced interest or pleasure (Table 4). Again, using only a single item led to poorer performance against each of the criterion measures. Against the BSI-18, specificity and NPV were high, and sensitivity was acceptable, although PPV was lower. Sensitivity of the anhedonia item against the other measures was not considered acceptable and was poor against the GHQ-12 and DT. Analysis of the results from only the oncology patients showed the same aforementioned pattern. Screening for Depression Using the Two-Question Depression Screen The 2Q depression screen performed similarly against both the HADS-D and BSI-D, with high sensitivity and NPV, and acceptable specificity, although PPV was lower (Table 5). Results were similar to those shown for the full HADS and BSI-18. Analysis of the results from only the oncology patients showed the same aforementioned pattern, except that the PPV was higher. Screening for Depression Using the One-Question Depression Screen The depression question demonstrated high sensitivity and NPV, and acceptable specificity against the BSI-D, although the PPV was lower (Table 5). A similar pattern was seen against the HADS-D with high NPV, acceptable sensitivity and specificity, and lower PPV. Analysis

6 Vol. 38 No. 2 August 2009 UK Validation of a 2Q Depression Screen 239 Table 1 Participant Characteristics Total Sample (n ¼ 171) Oncology Clinic (n ¼ 160) Palliative Care Clinic (n ¼ 11) Age: mean (SD) 60 (13.7) 60 (13.3) 55 (5.4) Gender (%) Male 80 (47) 76 (47) 4 (36) Female 91 (53) 84 (54) 7 (63) Ethnic group (%) White 144 (84) 134 (84) 10 (91) Nonwhite 24 (14) 23 (14) 1 (9) Other 3 (2) 3 (2) 0 Occupation (%) Managerial and professional occupations 66 (39) 59 (37) 7 (64) Intermediate occupations 32 (19) 30 (19) 2 (18) Small employers/own account workers 10 (6) 9 (6) 1 (9) Lower supervisory and technical occupations 3 (2) 3 (2) 0 Semi-routine and routine occupations 40 (23) 39 (24) 1 (9) Unclassified/not stated 20 (11) 20 (12) 0 Educational level (%) Not finished secondary school 37 (22) 36 (23) 1 (9) Secondary school 29 (17) 28 (18) 1 (9) College or further education 27 (16) 26 (16) 1 (9) Degree 60 (35) 52 (33) 8 (73) Other/not stated 15 (9) 15 (9) 0 Marital status (%) Married/living with partner 104 (61) 100 (63) 4 (36) Living without partner 62 (36) 55 (34) 7 (64) Unknown 5 (3) 5 (3) 0 Home ownership (%) Owned 121 (71) 115 (72) 6 (55) Rented 48 (28) 43 (27) 5 (45) Unknown 2 (1) 2 (1) 0 Employment status (%) Employed 48 (27) 46 (29) 2 (18) Self-employed 17 (10) 16 (10) 1 (9) Unemployed 8 (5) 6 (4) 2 (18) Home manager 7 (4) 7 (4) 0 Retired 72 (42) 68 (42) 4 (37) On sick leave 10 (6) 10 (6) 0 Student 1 (1) 1 (1) 0 Other 8 (5) 6 (4) 2 (18) SD ¼ standard deviation. of the results from only the oncology patients showed the same aforementioned pattern, except that the PPV was higher. Screening for Depression Using the One-Question Anhedonia Screen The anhedonia question demonstrated high specificity and NPV, and acceptable sensitivity against the BSI-D, although the PPV was lower (Table 5). However, sensitivity of the anhedonia question against HADS-D was not considered acceptable. Analysis of the results from only the oncology patients showed the same aforementioned pattern, except that the PPV was higher. Summary of the Main Findings The findings show that, when screening for psychological distress, to maximize both sensitivity and specificity, the 2Q depression screen should be used rather than either question alone. Against the BSI-18, GHQ-12, and HADS, sensitivity and specificity were shown to be acceptable to high. The high NPV indicates that a high proportion of patients who are not identified as having distress by the tool are also not identified as being distressed by the criterion measures. Hence the 2Q depression screen performs very well at ruling out psychological distress in cancer populations. The lower PPV indicates that a high proportion of those indicated to have distress on this ultrashort screen are identified as being distressed by the GHQ-12 and the DT but not by the other two criterion measures. In further analysis looking at the ability of the ultrashort screening instruments to be

7 240 Low et al. Vol. 38 No. 2 August 2009 Table 2 Sensitivity, Specificity, PPV, NPV, FPR, and FNR of the 2Q Screening Item Against Each Criterion Measure a for Psychological Distress Sensitivity Specificity PPV NPV FPR FNR HADS (n ¼ 160) 89 (84e94) 79 (73e85) 63 (56e70) 95 (92e98) 21 (15e27) 11 (6e16) GHQ-12 (n ¼ 162) 78 (7e18) 86 (81e91) 80 (74e86) 85 (80e91) 14 (9e19) 22 (16e28) BSI-18 (n ¼ 163) 89 (84e94) 70 (63e77) 37 (30e44) 97 (94e99) 30 (23e37) 11 (6e16) DT (n ¼ 154) 68 (61e75) 82 (76e88) 71 (64e78) 79 (73e85) 18 (12e24) 32 (25e39) HADS (n ¼ 150) 92 (88e96) 79 (72e85) 60 (52e68) 97 (94e99) 21 (14e28) 9 (4e14) GHQ-12 (n ¼ 151) 80 (74e86) 87 (82e92) 80 (74e86) 87 (82e92) 13 (7e18) 20 (14e26) BSI-18 (n ¼ 152) 91 (86e96) 71 (64e78) 36 (28e44) 98(96e100) 29 (22e36) 9 (4e14) DT (n ¼ 143) 67 (59e74) 81 (75e87) 68 (60e76) 80 (73e87) 19 (13e25) 33 (25e41) a With a cutoff of 0 vs. 1. used to screen for depression, our findings show that, to maximize both sensitivity and specificity, either the 2Q depression screen or the 1Q depression screen should be used, but not the 1Q anhedonia screen. High NPV for the 2Q depression screen, 1Q depression screen, and 1Q anhedonia screen indicate that all three measures were good at ruling out depression in a cancer population, but the low PPV would indicate that they were poorer at identifying cases of depression. Discussion This study is the first in the United Kingdom to consider the relationship of the ultrashort 2Q depression screen to standard reference tests to screen for the wider concept of psychological distress in addition to depression. It is the first study to consider the use of both the single- and two-item depression questions in a mixed-stage cancer population as opposed to a palliative or terminally ill population. Unlike previous studies, a power calculation was included to estimate the required sample size to evaluate concurrent validity. As with studies in other countries, 16,17,19 the results confirm the validity of the 2Q depression screen as a potential screen for psychological distress. Although our sensitivity and specificity values are not as high as those obtained in a Canadian study (100% and 98%, respectively), 16 they are similar to those obtained in studies conducted in Ireland 17 and Japan. 19 Our findings indicate that the 2Q depression screen is superior to using either item alone. The high NPV indicates that a patient who is not identified as a case with the 2Q depression screen is unlikely to be identified as a case with any of the four criterion measures. The high sensitivity suggests that if a patient is identified as a case by one of the criterion measures, they are very likely to be detected as a case by the 2Q depression screen. The lower PPV suggests that the 2Q screen identified more cases than the criterion measures, and a more detailed psychological assessment would be required to confirm psychological distress. 12,15,20 High PPV for the GHQ-12 and the DT only would Table 3 Sensitivity, Specificity, PPV, NPV, FPR, and FNR of the Depression Question Against Each Criterion Measure for Psychological Distress Sensitivity Specificity PPV NPV FPR FNR HADS (n ¼ 160) 82 (76e88) 85 (79e91) 69 (62e76) 92 (88e96) 15 (9e21) 18 (12e24) GHQ-12 (n ¼ 162) 67 (60e74) 89 (84e94) 82 (76e88) 79 (73e86) 11 (6e16) 33 (26e40) BSI-18 (n ¼ 163) 81 (75e87) 76 (69e83) 40 (32e48) 95 (92e98) 24 (17e31) 19 (13e25) DT (n ¼ 154) 65 (57e72) 89 (84e94) 80 (74e86) 79 (73e85) 11 (6e16) 35 (27e43) HADS (n ¼ 149) 84 (78e90) 86 (80e92) 67 (59e74) 94 (90e98) 14 (8e20) 16 (10e22) GHQ-12 (n ¼ 151) 68 (61e75) 90 (85e94) 82 (76e88) 82 (76e88) 10 (5e15) 32 (25e39) BSI-18 (n ¼ 152) 82 (76e88) 76 (69e83) 39 (31e47) 97 (94e100) 24 (17e31) 18 (12e24) DT (n ¼ 144) 63 (55e71) 89 (84e94) 77 (70e84) 80 (73e87) 11 (6e16) 37 (29e45)

8 Vol. 38 No. 2 August 2009 UK Validation of a 2Q Depression Screen 241 Table 4 Sensitivity, Specificity, PPV, NPV, FPR, and FNR of the Anhedonia Question Against Each Criterion Measure for Psychological Distress Sensitivity Specificity PPV NPV FPR FNR HADS (n ¼ 161) 64 (57e71) 87 (82e92) 66 (59e73) 86 (81e91) 13 (8e18) 36 (29e43) GHQ-12 (n ¼ 163) 57 (49e65) 92 (88e96) 83 (77e89) 75 (68e82) 8 (4e12) 43 (35e51) BSI-18 (n ¼ 164) 70 (63e77) 81 (75e87) 42 (34e50) 93 (89e97) 19 (13e25) 30 (23e37) DT (n ¼ 154) 48 (40e56) 87 (82e92) 71 (64e78) 72 (65e79) 13 (8e18) 52 (44e60) HADS (n ¼ 150) 66 (58e74) 87 (82e93) 63 (55e71) 88 (83e93) 13 (8e18) 34 (26e42) GHQ-12 (n ¼ 152) 58 (50e66) 91 (86e96) 81 (75e87) 77 (70e84) 9 (4e14) 42 (34e50) BSI-18 (n ¼ 153) 74 (67e81) 82 (76e88) 41 (33e49) 95 (91e98) 18 (12e24) 26 (19e33) DT (n ¼ 144) 48 (40e56) 87 (81e93) 68 (60e76) 74 (67e81) 13 (8e18) 52 (44e60) indicate that our ultrashort screens were measuring the same types of psychological distress as the GHQ-12 and the DT, but different from those identified by the BSI-18 and the HADS. The HADS and the BSI-18 may be picking up anxiety in the global score. In comparing the performance of the ultrashort 2Q or 1Q screening instruments with reference to the HADS-D or the BSI-D to screen specifically for depression, our findings showed the validity of both the 2Q and the 1Q depression screens, but not the 1Q anhedonia screen. However, allthough our findings on the 1Q depression screen supported the findings of some studies, 16,17 others have queried the use of this item as a screening tool for depression 18 because of its poor ability to identify depression in palliative care patients. The main limitation of our study is the use of the HADS, BSI-18, and GHQ-12 as reference standards as opposed to the psychiatric semistructured interview used in previous studies. However, our study primarily aimed to use the 2Q depression items as a screening tool for a broad concept of psychological distress. 25 Other limitations include the restricted occupational range of the sample partly affected by the exclusion criteria and hospital sites. In addition, the requirement by the ethics committee that patients were initially approached by health care professionals added a possible bias against a wider mix, and slowed recruitment substantially. However, the sample was equally balanced on gender, contained 13% patients from a nonwhite ethnic background, and the age range reflected that of the target population. The sample size was smaller than the original power calculation, although retrospective calculations indicate that the sample Table 5 Sensitivity, Specificity, PPV, NPV, FPR, and FNR of the 2Q Screening Item, the Depression Question, and the Anhedonia Question Against the Two Criterion Measures for Depression Sensitivity Specificity PPV NPV FPR FNR 2Q screening item HADS-D (n ¼ 165) 84 (78e90) 73 (66e80) 48 (40e56) 94 (90e98) 27 (20e34) 16 (10e22) BSI-D (n ¼ 165) 94 (90e98) 72 (65e79) 44 (36e52) 98 (96e100) 28 (21e35) 6 (2e10) HADS-D (n ¼ 154) 86 (81e91) 79 (73e85) 60 (52e68) 94 (90e98) 21 (15e27) 14 (9e19) BSI-D (n ¼ 154) 96 (93e99) 72 (65e79) 40 (32e48) 99 (97e100) 28 (21e35) 4 (1e7) Depression question HADS-D (n ¼ 165) 74 (67e81) 78 (72e84) 50 (42e58) 91 (87e95) 22 (16e28) 26 (19e33) BSI-D (n ¼ 165) 90 (85e95) 79 (73e85) 50 (42e58) 97 (94e100) 21 (15e27) 10 (5e15) HADS-D (n ¼ 154) 76 (69e83) 84 (78e90) 64 (56e72) 90 (85e95) 16 (10e22) 24 (17e31) BSI-D (n ¼ 154) 92 (88e96) 79 (73e85) 46 (38e54) 98 (96e100) 21 (15e27) 8 (4e12) Anhedonia question HADS-D (n ¼ 165) 66 (67e81) 84 (78e90) 54 (46e62) 89 (84e94) 16 (10e22) 34 (27e41) BSI-D (n ¼ 165) 74 (67e81) 83 (77e89) 50 (42e58) 93 (89e97) 17 (11e23) 26 (19e33) HADS-D (n ¼ 154) 69 (62e76) 89 (84e94) 69 (62e76) 89 (84e94) 11 (6e16) 31 (24e38) BSI-D (n ¼ 154) 80 (74e86) 83 (77e89) 48 (40e56) 96 (93e99) 17 (11e23) 20 (14e26)

9 242 Low et al. Vol. 38 No. 2 August 2009 was of sufficient size for the results to be interpreted with confidence. Furthermore, as our study question was interested in validating the 2Q depression screen across a cancer population with supportive and palliative care needs, we did not collect any information on disease site, stage, or length of disease, as we were not planning to do subanalyses on these variables. Finally, unlike previous studies, we delivered the 2Q depression screen in a written questionnaire format, and responses may have been different if administered as an interview. Nevertheless, the brief nature of the 2Q depression screen makes it likely to be successfully implemented universally in a busy clinical setting where medical urgency may make longer and more complex assessments impossible. However, the lower PPV suggests the need for clinical procedures and adequate resources to ensure that any person scoring highly on the measure is referred to a suitably qualified health professional for a more detailed and complex psychological assessment. Acknowledgments The authors would like to acknowledge Marie Curie Cancer Care for funding; Professors Jonathan Lederman and Daniel Hochhauser, Dr. John Bridgewater, Dr. Mary McCormack, Mr. Tim Mould, Miss Adeola Olaitan, Miss Nicola MacDonald, Dr. David Chao, Dr. Tim Meyer, and all the patients and staff at the clinics for their generous participation and active involvement; the North London Cancer Network for its support for this study; Mr. Robert Blizard for his statistical advice; and Beth Downe for her support in producing the manuscript. This work was undertaken at UCLH/UCL, which received a proportion of funding from the Department of Health s NIHR Biomedical Research Centres funding scheme. Contributors: J.L. and S.G. were the principal investigators of this study, responsible for its design, project supervision, data analysis and interpretation, and the writing of the manuscript. R.W. was responsible for the data analysis and interpretation and contributed to the manuscript writing. E.D. was responsible for data collection and contributed to data analysis, data interpretation. and manuscript writing. V.B. contributed to the data collection, data analysis, data interpretation. and manuscript writing. A.T. contributed to the study design, data analysis, and manuscript writing. L.J. contributed to the study design, data analysis, data interpretation. and manuscript writing, and oversaw the project. J.L. is the guarantor for this study. References 1. Maguire P. Improving the detection of psychiatric problems in cancer patients. Soc Sci Med 1985; 20(8):819e Zabora J, Brintzenhofeszoc K, Curbow B, Hooker C, Piantadosi S. The prevalence of psychological distress by cancer site. Psychooncology 2001;10:19e Bultz BD, Carlson LE. Emotional distress: the sixth vital sign in cancer care. J Clin Oncol 2005; 23(26):6440e Velikova G, Booth L, Smith AB, et al. Measuring quality of life in routine oncology practice improves communication and patient well-being: a randomized controlled trial. J Clin Oncol 2004;22:714e Zigmond AS, Snaith RP. The Hospital Anxiety and Depression Scale. Acta Psychiatr Scand 1983; 67:361e Goldberg D, Williams P. A user s guide to the general health questionnaire. Windsor, England: NFER-Nelson, Berard RMF, Boermeester F, Viljoen G. Depressive disorders in an out-patient oncology setting: prevalence, assessment, and management. Psychooncology 1998;7:112e Roth AJ, Kornblith AB, Batel-Copel L, et al. Rapid screening for psychologic distress in men with prostrate carcinoma. Cancer 1998;82:1904e Lloyd-Williams M, Spiller J, Ward J. Which depression screening tools should be used in palliative care? Palliat Med 2003;17:40e Lloyd-Williams M, Friedman T, Rudd N. An analysis of the validity of the Hospital Anxiety and Depression Scale as a screening tool in patients with advanced cancer. J Pain Symptom Manage 2001;22:990e Hall A, Hern RA, Fallowfield L. Are we using appropriate self-report questionnaires for detecting anxiety and depression in women with early breast cancer? Eur J Cancer 1999;35:79e Mitchell A. Accuracy of distress thermometer and other ultra-short methods of detecting cancer-- related mood disorders: pooled results from 38 analyses. J Clin Oncol 2007;25:4670e Arroll B, Khin N, Kerse N. Screening for depression in primary care with two verbally asked

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