/clinical/,/clinical/cckm-tools/,/clinical/cckm-tools/content/,/clinical/cckm-tools/content/questionnaires/,/clinical/cckm-tools/content/questionnaires/related/,

/clinical/cckm-tools/content/questionnaires/related/name-97118-en.cckm

201606168

page

100

UWHC,UWMF,

Tools,

Clinical Hub,UW Health Clinical Tool Search,UW Health Clinical Tool Search,Questionnaires,Related

The Patient Health Questionnaire-2 Validity of a two-Item Screener

The Patient Health Questionnaire-2 Validity of a two-Item Screener - Clinical Hub, UW Health Clinical Tool Search, UW Health Clinical Tool Search, Questionnaires, Related


MEDICAL CARE
Volume 41, Number 11, pp 1284-1292
?2003 Lippincott Williams & Wilkins, Inc.
The Patient Health Questionnaire-2
Validity of a Two-Item Depression Screener
KURT KROENKE, MD,* ROBERT L. SPITZER, MD,t AND JANET B. W. WILLIAMS, DSWt
BACKGROUND. A number of self-
administered questionnaires are available for
assessing depression severity, including the
9-item Patient Health Questionnaire depres-
sion module (PHQ-9). Because even briefer
measures might be desirable for use in busy
clinical settings or as part of comprehensive
health questionnaires, we evaluated a 2-item
version of the PHQ depression module, the
PHQ-2.
METHODS. The PHQ-2 inquires about the
frequency of depressed mood and anhedonia
over the past 2 weeks, scoring each as 0 ("not at
all") to 3 ("nearly every day"). The PHQ-2 was
completed by 6000 patients in 8 primary care
clinics and 7 obstetrics-gynecology clinics.
Construct validity was assessed using the 20-
item Short-Form General Health Survey, self-
reported sick days and clinic visits, and
symptom-related difficulty. Criterion validity
was assessed against an independent struc-
Depression is a prevalent and disabling condi-
tion in the general medical setting. Although
many patients with depression receive care exclu-
sively in the primary care rather than mental
health sector, up to half of depression cases in
primary care go unrecognized.1’2 The U.S. Preven-
tive Services Task Force recently concluded that
From the *Regenstrief Institute for Health Care and
Department of Medicine, Indiana University, Indianap-
olis, Indiana.
From the tNew York State Psychiatric Institute and
Department of Psychiatry, Columbia University, New
York, NY.
The development of the PHQ-2 was underwritten by
an educational grant from Pfizer US Pharmaceuticals
tured mental health professional (MHP) inter-
view in a sample of 580 patients.
RESULTS. AS PHQ-2 depression severity in-
creased from 0 to 6, there was a substantial
decrease in functional status on all 6 SF-20
subscales. Also, symptom-related difficulty,
sick days, and healthcare utilization increased.
Using the MHP reinterview as the criterion
standard, a PHQ-2 score >3 had a sensitivity of
83% and a specificity of 92% for major depres-
sion. Likelihood ratio and receiver operator
characteristic analysis identified a PHQ-2 score
of 3 as the optimal cutpoint for screening
purposes. Results were similar in the primary
care and obstetrics-gynecology samples.
CONCLUSION. The construct and criterion va-
lidity of the PHQ-2 make it an attractive mea-
sure for depression screening.
Key words: Depression; diagnosis; screen-
ing; mental disorders; functional status (Med
Care 2003;41:1284-1292)
there is sufficient evidence to recommend periodic
screening for depression.1 Numerous well-
validated questionnaires are available for depres-
sion screening and are similar in terms of their
operating characteristics as case-finding instru-
ments.2-4 One particularly popular instrument is
the 9-item depression module of the Patient
Inc., New York, NY. PRIME-MD is a trademark of Pfizer
Inc. Copyright held by Pfizer Inc.
Address correspondence and reprint requests to: Kurt
Kroenke, MD, Regenstrief Institute for Health Care,
RG-6, 1050 Wishard Blvd., Indianapolis, IN 46202.
E-mail: kkroenke@regenstrief.org
For a complimentary copy of PHQ materials that can
be reproduced, e-mail Robert Spitzer at
rls8@columbia.edu
1284
This content downloaded from 128.104.1.219 on Thu, 2 May 2013 09:14:20 AM
All use subject to JSTOR Terms and Conditions

THE PHQ-2 DEPRESSION SCREENER
Health Questionnaire, the PHQ-9. Validated in
6000 patients, the PHQ-9 serves as both a depres-
sion severity measure as well as a diagnostic
instrument for the Diagnostic and Statistical Man-
ual of Mental Disorders, 4th edition (DSM-IV),
depressive disorders.5
However, even shorter measures could be de-
sirable in some circumstances. First, the busy
nature and competing demands of primary care
practice make efficiency a particularly important
attribute of any new measure.6-8 Second, depres-
sion is only one of the many disorders for which
screening in primary care is encouraged. Thus,
brief depression measures could be incorporated
as part of comprehensive health questionnaires
administered to either patients new to a practice or
established patients on a periodic basis. Keeping
to a minimum the number of items asked about a
single disorder is an important factor to maintain a
reasonable length for such questionnaires. The
same might be true for research studies in which
depression is a secondary rather than primary
variable, and asking a few rather than many items
can reduce respondent burden.
Therefore, we examined the operating charac-
teristics of 2 items from the PHQ-9, depressed
mood and anhedonia, which we call the PHQ-2.
Previous research has shown that a single ques-
tion about depressed mood has a sensitivity of
85% to 90% for major depression,3,9 and adding a
second question about anhedonia increases the
sensitivity to 95%.3 The PHQ-2 asks respondents
to estimate the frequency of these 2 symptoms
over the past 2 weeks with 4 response options
ranging from "not at all"to "nearly everyday."Data
are analyzed from the 2 major PHQ studies in-
volving 3000 patients in 8 primary care clinics and
3000 patients in 7 obstetrics-gynecology clin-
ics.10,11 Our aims were to assess the criterion and
construct validity of the PHQ-2.
Methods
Description of the PHQ-9 and PHQ-2
The PHQ-9 is the 9-item depression module
from the full PHQ.5 Major depressive disorder is
diagnosed if 5 or more of the 9 depressive symp-
tom criteria have been present at least "more than
half the days" in the past 2 weeks, and one of the
symptoms is depressed mood or anhedonia. "Oth-
er depressive disorder" is diagnosed if 2, 3, or 4
depressive symptoms have been present at least
"more than half the days" in the past 2 weeks and
one of the symptoms is depressed mood or anhe-
donia. One of the 9 symptom criteria ("thoughts
that you would be better off dead or of hurting
yourself in some way") counts as one of the
diagnostic criteria for depressive disorders if
present at all, regardless of duration. Like with the
original PRIME-MD (Pfizer Inc., New York, NY),
the clinician is expected to rule out physical causes
of depression, normal bereavement, and history of
a manic episode.
The PHQ-2 includes the first 2 items of the
PHQ-9. The stem question is, "Over the last 2
weeks, how often have you been bothered by any
of the following problems?"The 2 items are "little
interest or pleasure in doing things" and "feeling
down, depressed, or hopeless." For each item, the
response options are "not at all," "several days,"
"more than half the days," and "nearly everyday,"
scored as 0, 1, 2, and 3, respectively. Thus, the
PHQ-2 score can range from 0 to 6.
PHQ Study Samples and Procedures
From May 1997 to November 1998, 3890 pa-
tients, 18 years or older, were invited to participate
in the PHQ Primary Care Study.10 There were 190
who declined to participate, 266 who started but
did not complete the questionnaire (often because
there was an inadequate time before seeing their
physician), and 434 whose questionnaires were
not entered into the dataset because the equiva-
lent of approximately one page (20 items) was not
completed. This resulted in the 3000 primary care
patients reported here (1422 from 5 general inter-
nal medicine clinics and 1578 from 3 family prac-
tice clinics). From May 1997 to March 1999, 3636
patients, 18 years or older, were approached to
participate in the PHQ Obstetrics-Gynecology
Study.l There were 245 patients who declined to
participate, 127 who started but did not complete
the questionnaire, and 264 whose questionnaires
were not entered into the dataset because the
equivalent of approximately one page was not
completed. This resulted in the 3000 subjects from
7 obstetrics-gynecology sites. The 2 PHQ studies
enrolled patients from 8 states (New York, Massa-
chusetts, Utah, Pennsylvania, Texas, Virginia, Ohio,
and Wisconsin) plus the District of Columbia.
All sites used 1 of 2 subject selection methods to
minimize sampling bias: either consecutive pa-
1285
Vol. 41, No. 11
This content downloaded from 128.104.1.219 on Thu, 2 May 2013 09:14:20 AM
All use subject to JSTOR Terms and Conditions

KROENKE ET AL
tients for a given clinic session or every nth patient
until the intended quota for that session was
achieved. Patient characteristics are summarized in
detail elsewhere.5 Briefly, the primary care sample
was 66% women, 21% minority in terms of race/
ethnicity, and had a mean age of 46 years. The
obstetrics-gynecology sample was 100% women,
61% minority, and had a mean age of 31 years. The
Institutional Review Board at each site approved
the study protocol.
Before seeing the physician, all patients com-
pleted the full self-administered PHQ. Also, they
completed the Medical Outcomes Study Short-
Form General Health Survey (SF-20).12 The SF-20
measures functional status in 6 domains (all scores
from 0-100, 100 = best health). Additionally,
patients estimated the number of physician visits
and disability days during the past 3 months.
Mental Health Professional Validation
Interviews
To determine the agreement of PHQ diagnoses
with those of mental health professionals (MHPs),
midway through the PHQ Primary Care Study, an MHP (a PhD clinical psychologist or 1 of 3 senior
psychiatric social workers) attempted to interview
by telephone all subsequently entered subjects
who had a telephone, agreed to be interviewed,
and could be contacted within 48 hours. All except
one site participated in these validation interviews.
The MHP was blinded to the results of the PHQ.
The rationale and further details of the MHP
telephone interview, which used the overview
from the SCID (structured clinical interview for
DSM-III-R)13 and diagnostic questions from the
PRIME-MD, are described in the original
PRIME-MD report.14 The 580 subjects who had a MHP interview within 48 hours of completing the
PHQ were, within each site, similar to patients not
reinterviewed in terms of demographic profile,
functional status, and frequency of psychiatric
diagnoses. Agreement between the PHQ diag-
noses and the MHP diagnoses was examined.
signed by the independent MHP structured psy-
chiatric interview. The latter is considered the
criterion standard and provides the most conser-
vative estimate of the operating characteristics of
the PHQ-2 score. Besides calculating sensitivity
and specificity of the PHQ-2 over various inter-
vals, we also determined likelihood ratios15 and
conducted receiver operating characteristic (ROC)
curve analysis16 as quantitative methods for com-
bining sensitivity and specificity into a single
metric.
Construct validity of the PHQ-2 as a measure of
depression severity was assessed by examining func-
tional status (the 6 SF-20 scales), disability days,
symptom-related difficulty, and healthcare utiliza-
tion (clinic visits) over the various PHQ-2 scores.
Analysis of covariance was used with PHQ-2 score
as the independent variable and adjusting for age,
sex, race, education, study site, and number of phys-
ical disorders. Bonferroni’s correction was used to
adjust for multiple comparisons.
Decrements in SF-20 scores were also exam-
ined in terms of effect size, which is the difference
in mean SF-20 scores, expressed as the number of
standard deviations, between each PHQ-2 score
and the reference group. The reference group was
subjects with a PHQ-2 score of 0, and the standard
deviation used was that of the entire sample.
Results
Distribution of PHQ-2 Scores According to
Depression Diagnostic Status
Table 1 shows the distribution of PHQ-2 scores
according to depression diagnostic status in the
580 patients interviewed by an MHP who was
blinded to the PHQ-2 results. Of the 41 subjects
who had major depressive disorder, 93% endorsed
at least some depressed mood (1 or greater) and
95% endorsed at least some anhedonia. The ma-
jority of patients (95%) with no depressive disor-
der had a PHQ-2 score less than 3, whereas most
patients (83%) with major depression had scores
of 3 or greater. Patients with other (ie, nonmajor)
depressive disorder exhibited more heterogeneity
in their PHQ-2 scores.
Analysis
For analyses assessing the operating character-
istics of various PHQ-2 cutpoints, diagnostic sta-
tus (major depressive disorder, other depressive
disorder, or no depressive disorder) was that as-
Criterion Validity of the PHQ-2 Assessed by Mental Health Professional Interview
Table 2 displays the sensitivity, specificity, pos-
itive predictive value, and likelihood ratios for
1286
MEDICAL CARE
This content downloaded from 128.104.1.219 on Thu, 2 May 2013 09:14:20 AM
All use subject to JSTOR Terms and Conditions

THE PHQ-2 DEPRESSION SCREENER
TABLE 1. Frequency Distribution of Depressed Mood and Anhedonia Items and PHQ-2 Score in a
Subset of 580 Patients Who Had an MHP Interview in PHQ Primary Care Study*
Major Depression Other Depression No Depression
(N= 41) (N = 65) (N = 474)
Item or PHQ-2 Score N % N % N %
Depressed mood
0 (not at all) 3 7.3 14 21.5 338 71.3
1 (several days) 7 17.1 23 35.4 114 24.1
2 (more than half 16 39.0 17 26.2 13 2.7
3 (nearly every day) 15 36.6 11 16.9 9 1.9
Anhedonia
0 (not at all) 2 4.9 16 24.6 364 76.8
1 (several days) 8 19.5 25 38.5 89 18.8
2 (more than half) 10 24.4 13 20.0 16 3.4
3 (nearly every day) 21 51.2 11 16.9 5 1.1
PHQ-2 Score
0 1 2.4 9 13.8 310 65.4
1 2 4.9 7 10.8 71 15.0
2 4 9.8 17 26.2 71 15.0
3 4 9.8 8 12.3 10 2.1
4 8 19.5 13 20.0 6 1.3
5 11 26.8 9 13.8 5 1.1
6 11 26.8 2 3.1 1 0.2
*Depression diagnostic status was determined in 580 primary care patients by having a mental health
professional (MHP) who was blinded to the PHQ-2 score administer a structured psychiatric interview.
PHQ, Patient Health Questionnaire.
different PHQ-2 scores in diagnosing depressive
disorders in the 580 patients who had an MHP
interview. In this sample with a 7% prevalence of
major depressive disorder, the positive predictive
value for major depressive disorder ranged from
21% for a PHQ-2 cutpoint of 2 to 56% for a
TABLE 2. Operating Characteristics of PHQ-2 as a Screener for Depressive Disorders in 580 Patients Who Had an Independent Mental Health Professional Interviewt
Major Depressive Disorder (N = 41) Any Depressive Disorder (N = 106)
Positive Positive
Predictive Likelihood Predictive Likelihood
PHQ-2 Sensitivity Specificity Value Ratio Sensitivity Specificity Value Ratio
1 97.6 59.2 15.4 0.3 90.6 65.4 36.9 0.6
2 92.7 73.7 21.1 0.6 82.1 80.4 48.3 1.3
3 82.9 90.0 38.4 2.9 62.3 95.4 75.0 5.4
4 73.2 93.3 45.5 5.5 50.9 97.9 81.2 15.7
5 53.7 96.8 56.4 10.3 31.1 98.7 84.6 17.9
6 26.8 99.4 78.6 48.2 12.3 99.8 92.9 58.1
tSensitivity, specificity, and positive predictive value refers to a threshold PHQ-2 score (ie, all subjects with that
score or higher), whereas likelihood ratio refers to a discrete PHQ-2 score (ie, only subjects with that specific score).
For example, 82.9% of patients with major depressive disorder have a PHQ-2 score of 3 or greater (sensitivity),
90% of patients without major depressive disorder have a score of less than 3 (specificity), 38.4% of patients with a
score of 3 or greater have major depressive disorder (positive predictive value), and a score of 3 is 2.9 times more
likely in patients with than without major depressive disorder (likelihood ratio).
PHQ, Patient Health Questionnaire.
1287
Vol. 41, No. 11
This content downloaded from 128.104.1.219 on Thu, 2 May 2013 09:14:20 AM
All use subject to JSTOR Terms and Conditions

KROENKE ET AL
cutpoint of 5. The positive predictive value for any
depressive disorder (which had a prevalence of
18%) ranged from 48% for a PHQ-2 cutpoint of 2
to 85% for a cutpoint of 5. At a cutpoint of 3 or
higher, the PHQ-2 had a likelihood ratio for major
depression of 2.92, nearly identical to the overall
likelihood ratio of 2.86 reported for 9 other depres-
sion case finding instruments in a meta-analysis of
the literature.2 Regarding concordance with the
MHP interview, a PHQ-2 cutpoint of 3 or greater
was comparable to the PHQ-9 diagnostic algo-
rithm for any depressive disorder (kappa of 0.62
vs. 0.58) as well as major depressive disorder
(kappa of 0.48 vs. 0.54).
ROC analysis showed that the area under the
curve (AUC) for the PHQ-2 in diagnosing major
depressive disorder was 0.93 (vs. 0.95 for the
longer PHQ-9). The AUC of the PHQ-2 for diag-
nosing any depressive disorder was 0.90 (vs. 0.92
for the PHQ-9). Although the AUC for both major
and any depressive disorder was similar for
women and men, age had a modest effect. The
AUC for major depressive disorder was somewhat
greater in subjects less than 60 years compared
with those 60 years and older (0.94 vs. 0.86),
whereas for any depressive disorder, younger sub-
jects had a lower AUC (0.88 vs. 0.95).
Construct Validity of the PHQ-2 Assessed
by Functional Status and Other Measures
As shown in Table 3, there was a strong asso-
ciation between increasing PHQ-2 depression se-
verity scores and worsening function on all 6
SF-20 scales. Several findings should be noted.
First, results were essentially the same for both the
primary care and obstetrics-gynecology samples.
Second, the monotonic decrease in SF-20 scores
with increasing PHQ-2 scores were greatest for
the scales that previous studies have shown
should be most strongly related to depression, ie,
mental health, followed by social, overall, and role
functioning, with a lesser relationship to pain and
physical functioning.14 Third, most pairwise com-
parisons within each SF-20 scale between succes-
sive PHQ-2 levels were highly significant.
Figure 1 illustrates graphically the relationship
between increasing PHQ-2 scores and worsening
functional status. Decrements in SF-20 scores are
shown in terms of effect size. Effect sizes of 0.5 and
0.8 are typically considered moderate and large
between-group differences, respectively.17 Figure 1
shows effect sizes for the primary care sample;
results for the obstetrics-gynecology sample (not
displayed) were similar. When the PHQ-2 was examined as a continu-
ous variable, its strength of association with the
SF-20 scales was concordant with the pattern seen
in Figure 1. In both the primary care and obstet-
rics-gynecology samples, the PHQ-2 correlated
most strongly with mental health (0.70 and 0.63),
followed by general health perceptions (0.47 and
0.46), social functioning (0.46 and 0.36), physical
functioning (0.37 and 0.36), role functioning (0.37
and 0.29), and bodily pain (0.26 and 0.31).
Table 4 shows the association between PHQ-2
severity levels and 3 other measures of construct
validity: self-reported disability days, clinic visits,
and the general amount of difficulty patients at-
tribute to their symptoms. Greater levels of de-
pression severity were associated with a mono-
tonic increase in disability days, healthcare
utilization, and symptom-related difficulty in ac-
tivities and relationships.
Discussion
Our study provides strong evidence for the
validity of the PHQ-2 as a brief depression screen-
ing measure. Criterion validity was demonstrated
by the fact that the operating characteristics of the
PHQ-2 compared favorably with an independent
MHP interview in a sample of 585 patients. Con-
struct validity was established by the strong asso-
ciation between PHQ-2 scores and functional
status, disability days, and symptom-related diffi-
culty. The sample of 6000 patients from 15 geo-
graphically dispersed clinics as well as the similar-
ity of findings in 2 different patient populations
(primary care and obstetrics-gynecology) en-
hances the generalizability of our findings.
The PHQ-9 would still be the preferred instru-
ment when the intent is either to definitively
diagnose depressive disorders or to assess depres-
sion outcomes in response to treatment. This is
because the PHQ-9 includes all 9 symptom crite-
ria necessary for establishing DSM-IV depressive
disorder diagnoses and provides a wider range of
depressive symptom severity scores (0-27) com-
pared with the PHQ-2 (0-6). However, in many
settings, the purpose is not to establish final
diagnoses or to monitor depression severity, but
rather to screen for depression in a "first step"
approach. Even briefer versions might be desirable
1288
MEDICAL CARE
This content downloaded from 128.104.1.219 on Thu, 2 May 2013 09:14:20 AM
All use subject to JSTOR Terms and Conditions

THE PHQ-2 DEPRESSION SCREENER
TABLE 3. Relationship between PHQ-2 Depression Score and SF-20 Health-Related Quality-of-Life
Scales in Patients in the PHQ Primary Care (n = 3000) and PHQ Obstetrics-Gynecology (n = 3000)
Studiest
Mental Social Role General Pain Physical
Primary Ob- Primary Ob- Primary Ob- Primary Ob- Primary Ob- Primary Ob-
PHQ-2 Care Gyn Care Gyn Care Gyn Care Gyn Care Gyn Care Gyn
Score Mean SF-20 scale score
0 82.1 82.2 90.9 91.7 84.1 88.3 68.8 74.9 65.1 73.7 81.5 85.3
1 69.8 73.8 85.4 87.1 76.9 84.4 58.8 65.7 59.3 65.8 75.1 81.1
2 58.7 62.4 74.8 80.8 60.3 76.9 48.6 57.0 52.9 58.8 68.5 77.3
3 52.6 53.6 60.6 74.1 50.2 70.7 38.5 50.5 46.9 54.7 61.8 76.7
4 46.5 50.2 57.6 67.1 51.3 57.7 39.5 43.4 49.7 53.5 61.4 68.0
5 39.2 43.9 59.7 62.0 39.5 53.1 35.7 41.8 46.2 43.8 58.5 63.5
6 33.3 40.3 47.4 54.7 37.0 49.3 30.2 36.2 43.7 48.0 57.8 65.2
tSF-20 scores are adjusted for age, sex, race, education, study site, and number of physical disorders.
To simplify this table, standard deviations and P values are not shown. However, most pair-wise comparisons of
mean SF- 20 scores between each PHQ-9 level within each scale are significant at P < 0.05 using Bonferroni’s
correction for multiple comparisons.
PHQ, Patient Health Questionnaire; SF-20, 20-item Short- Form General Health Survey.
when the aim is to include just a few depression
questions in multipurpose health questionnaires.
The U.S. Preventive Services Task Force recently
recommended depression screening as part of
routine care.’ However, brevity is essential to
accomplish this in the busy general medical set-
ting where patient volume is high, most visits are
brief, and depression is simply one of many con-
ditions that the primary care clinician is responsi-
ble for recognizing and managing.6-8
Others have shown that 1 or 2 questions about
depressed mood and, possibly, anhedonia are
quite sensitive as a first-stage depression screen-
ing procedure.2-4 ,918 Whereas Whooley and col-
leagues also found that the 2 depression items of
the original PRIME-MD performed similarly to
-
-0.5 -
-1 -
-1.5 -
-2 -
-2.5
I SF-20 Scale |
K Pain
Physical
Role
* General
Social
Mental
1 2 3 4 5 6
PHQ-2 Score
FIG. 1. Relationship between depression severity as measured by the PHQ-2 and decline in functional status as measured by the 6 subscales of the SF-20. The decrement in SF-20 scores is shown as the difference between each
PHQ-2 score and the reference group (ie, those with a PHQ-2 of 0). Effect size is the difference in group means divided
by the standard deviation of the entire sample.
1289
Vol. 41, No. 11
This content downloaded from 128.104.1.219 on Thu, 2 May 2013 09:14:20 AM
All use subject to JSTOR Terms and Conditions

KROENKE ET AL
TABLE 4. Relationship between PHQ-2 Depression Score and Disability Days, Symptom-Related
Difficulty, and Clinic Visits in the PHQ Primary Care, and Obstetrics-Gynecology Studies
Mean Disability Days* Mean Physician Visits* Symptom-Related Difficulty (%)t
PHQ-2 Primary Obstetrics- Primary Obstetrics- Primary Obstetrics-
Score Care Gynecology Care Gynecology Care Gynecology
0 2.7 2.3 1.1 0.9 2.1% 1.4%
1 4.6 3.0 1.3 1.0 6.4% 2.2%
2 9.0 6.0 1.9 1.2 11.9% 3.7%
3 9.4 6.8 1.9 2.0 24.5% 17.1%
4 12.8 12.8 2.5 1.4 31.3% 25.0%
5 16.7 13.3 2.3 1.8 53.1% 36.6%
6 25.0 16.8 3.0 1.9 57.0% 48.4%
*Disability days refers to number of days in past 3 months that patients’ symptoms interfered with their usual
activities. Physician visits refers to past 3 months also. Both are self-reported. Means are also adjusted for age, sex,
race, education, study site, and number of physical disorders
tResponse to single question: "How difficult have these problems made it for you to do your work, take care of
things at home, or get along with other people?" The 4 response categories are "not difficult at all," "somewhat
difficult," "very difficult," and "extremely difficult." Symptom-related difficulty in this table refers to those patients
reporting "very" or "extremely" difficult.
To simplify this table, standard deviations and P values are not shown. However, most pairwise comparisons
between each PHQ-9 severity level for a given variable are significant at P < 0.05 using Bonferroni’s correction for
multiple comparisons.
PHQ, Patient Health Questionnaire.
longer case-finding instruments,3 our findings
build on this earlier work for 4 important reasons.
First, our PHQ studies included 6000 patients from
multiple clinics representing a more diverse pop-
ulation, whereas Whooley et al. studied 536 pa-
tients who were mostly male (97%) veterans
drawn from a single clinic. Second, the original
PRIME-MD evaluated by Whooley et al. was de-
signed as a 2-stage procedure in which positive
responses on the patient questionnaire prompted
a structured interview using a clinician evaluation
guide. To maximize sensitivity, the timeframe for
depressed mood and anhedonia was the past
month and the response options were simply yes
or no. Because the PHQ was intended to be
exclusively a patient self-report version of the
PRIME-MD, 2 important modifications were
made: the timeframe focused on the past 2 weeks
and the response options were expanded to 4 to
better delineate the number of days patients were
bothered by depressed mood and/or anhedonia.
This makes the one-stage PHQ more consistent
with DSM-IV criteria for depressive disorders and
therefore greatly improves the specificity of the
PHQ-2 compared with the 2 items of the
PRIME-MD with only a modest decline in sensi-
tivity. Specificity is an important consideration if
depression screening becomes more widespread,
because a large number of false-positives would
be difficult to handle efficiently in the context of
the large patient volume, short visits, and compet-
ing demands of primary care.6-8 Third, the char-
acteristic of better discriminating between de-
pressed and nondepressed patients is exemplified
by the PHQ-2’s higher AUC for major depression
of 0.93 compared with 0.82 for the 2-item
PRIME-MD as reported by Whooley et al. Because
this comparison is drawn from 2 different studies
(albeit both primary care), a head-to-head com-
parison of the operating characteristics of the
PHQ-2 versus the 2-item PRIME-MD would op-
timally be performed in the same patient popula-
tion. Fourth, the PHQ is rapidly replacing the
original PRIME-MD in both research and clinical
settings, so understanding the operating charac-
teristics of the PHQ-2 as a depression screener is
important for pragmatic reasons.
The operating characteristics of the PHQ-2
displayed at various cutpoints in Table 2 compare
favorably to 9 other case-finding instruments for
depression in primary care that have an overall
sensitivity of 84%, a specificity of 72%, and a
positive likelihood ratio of 2.86.2 At a cutpoint of 3,
the PHQ-2 has a sensitivity of 83%, a specificity of
90%, and a positive likelihood ratio of 2.9. Like-
wise, the positive predictive value of the PHQ-2
1290
MEDICAL CARE
This content downloaded from 128.104.1.219 on Thu, 2 May 2013 09:14:20 AM
All use subject to JSTOR Terms and Conditions

THE PHQ-2 DEPRESSION SCREENER
for major depression in our sample in which the
prevalence of major depression was 7% (similar to
other outpatient samples) ranged from 20% to
45% as the cutpoint was varied from 2 to 5. This
predictive value is similar to other instruments. Of
note, predictive value is related not only to a
measure’s sensitivity and specificity, but also to the
prevalence of depressive disorders.
The one depression measure that was used
concurrently with the PHQ-2 in our subjects was
the 5-item mental health scale of the SF-20, also
known as the Mental Health Inventory (MHI-5).
PHQ-2 scores were strongly correlated with
MHI-5 scores in both the primary care (r = .70)
and obstetrics-gynecology (r = .63) samples, an
association clearly illustrated in Table 3 and Figure
1. Berwick and colleagues used ROC analysis to
determine how well the MHI-5 and several other
measures discriminated between patients with
and without major depression.19 In their study, the
AUC was 0.89 for the MHI-5, 0.90 for the longer
MHI-18, 0.89 for the 30-item General Health
Questionnaire, and 0.80 for the 28-item Somatic
Symptom Inventory. In our study, the AUC for
major depression was 0.95 for the PHQ-9 and 0.93
for both the PHQ-2 and the MHI-5. Because an
AUC of 1.0 signifies a perfect test, it is unlikely that
other depression measures are diagnostically
superior.
Several caveats should be mentioned. First,
screening with the PHQ-2 is only a first step.
Patients who screen positive should be further
evaluated with the PHQ-9, other diagnostic in-
struments, or direct interview to determine
whether they meet criteria for a depressive disor-
der. High scores on the PHQ-2 alone would
typically not be a sufficient basis to initiate treat-
ment without diagnostic confirmation. Second,
subjects in our study completed the PHQ-2 as part
of the PHQ-9. An alternative design would be to
administer the PHQ-2 to one group of subjects
and the PHQ-9 to a second comparable group;
establishing similar operating characteristics with
this method would further validate the PHQ-2 as
a stand-alone depression screener. Third, picking
the optimal PHQ-2 cutpoint, like with any mea-
sure, is a trade-off between sensitivity and speci-
ficity. Although our analysis suggests a cutpoint of 3
provides a reasonable compromise, a cutpoint of
2 would enhance sensitivity, whereas a cutpoint
of 4 would improve specificity. One must be
cautious about overemphasizing sensitivity with
depression screening in primary care, partly be-
cause of the high volume of patients in primary
care and partly because a very sensitive cutpoint
coupled with a 5% to 10% prevalence of major
depression means that most patients screening
positive are false-positive cases.2 In settings in
which the prevalence of depression is much higher
(eg, psychiatric settings or hospitalized patients), a
different cutpoint might be considered.
A third caveat is that depression screening by
itself is not enough.20’21 Adequate follow up, de-
pression severity monitoring, and access when
needed to MHPs are required to detect medication
noncompliance, increase the antidepressant dos-
age, change or augment pharmacotherapy, or add
psychotherapy as needed.22-24 Even the U.S. Pre-
ventive Services Task Force concludes that depres-
sion screening is only effective if coupled with
systems changes to appropriately diagnose and
treat depression.1 In this sense, depression is no
different than many other medical disorders such
as diabetes, hypertension, and asthma, in which
detection must be combined with initial patient
education and activation and ongoing disease
monitoring and management, with a partnership
forged between the patient, the primary care pro-
vider, and the specialist.
Asking about depressed mood and anhedonia
would typically not require a paper questionnaire,
unless the items are included as part of a longer
health survey. Most clinicians could easily remem-
ber these 2 core symptoms. The PHQ-2 response
options simply allow patients to grade the amount
of time they have been bothered by either symp-
tom in the past 2 weeks, a core feature of the
DSM-IV criteria and one that distinguishes fleet-
ing from more persistent mood symptoms. Being
bothered by either depressed mood or anhedonia
"nearly everyday" or one symptom "more than
half the days" and the other symptom "several
days" would result in a PHQ-2 score of 3. This
score (or a lower score if other "red flags" of
depression are present8) could trigger administra-
tion of the full PHQ-9.
Brevity is a particularly attractive feature of
measures intended for use in clinical practice. In
the words of Mies van de Rohe, the modern
architect, "less is more." For example, one reason
for the popularity of the 4-item CAGE question-
naire (a questionnaire for alcoholism evaluation)25
could be its brevity compared with longer alcohol
screening measures. Likewise, simplifying depres-
sion screening to 2 questions enhances routine
1291
Vol. 41, No. 11
This content downloaded from 128.104.1.219 on Thu, 2 May 2013 09:14:20 AM
All use subject to JSTOR Terms and Conditions

KROENKE ET AL
inquiry about the most prevalent and treatable
mental disorder in primary care.
References
1. U.S. Preventive Services Task Force. Screening
for depression: recommendations and rationale. Ann
Intern Med 2002;136:760-764.
2. Mulrow CD, Williams JW, Gerety MB, et al.
Case-finding instruments for depression in primary care
settings. Ann Intern Med 1995;122:913-921.
3. Whooley MA, Avins AL, Miranda J, et al.
Case-finding instruments for depression: two questions
are as good as many. J Gen Intern Med 1997;12:439-445.
4. Williams JWJ, Noel PH, Cordes JA, et al. Is this
patient clinically depressed? JAMA 2002;287:1160-1170.
5. Kroenke K, Spitzer RL, Williams JBW. The
PHQ-9: validity of a brief depression severity measure.
J Gen Intern Med 2001;16:606-613.
6. Klinkman MS. Competing demands in psycho-
social care: a model for the identification and treatment
of depressive disorders in primary care. Gen Hosp
Psychiatry 1997;19:98-111.
7. Williams JW Jr. Competing demands: does care
for depression fit in primary care? J Gen Intern Med
1998;13:137-139.
8. Kroenke K. Discovering depression in medical
patients: reasonable expectations. Ann Intern Med
1997;126:463-465.
9. Williams JW, Mulrow CD, Kroenke K, et al.
Case-finding for depression improves patient outcomes:
results from a randomized trial in primary care. Am J Med 1999;106:36-43.
10. Spitzer RL, Kroenke K, Williams JBW, et al.
Validity and utility of a self-report version of PRIME-MD:
the PHQ primary care study. JAMA 1999;282:1737-1744.
11. Spitzer RL, Williams JBW, Kroenke K, et al.
Validity and utility of the Patient Health Questionnaire in
assessment of 3000 obstetric-gynecologic patients: the
PRIME-MD Patient Health Questionnaire Obstetrics-
Gynecology Study. Am J Obstet Gynecol 2000;183:759-
769.
12. Stewart AL, Hays RD, Ware JE. The MOS
Short-Form General Health Survey: reliability and valid-
ity in a patient population. Med Care 1988;26:724-732.
13. Spitzer RL, Williams JBW, Gibbon M, et al.
The Structured Clinical Interview for DSM-III-R (SCID).
Arch Gen Psychiatry 1992;49:624-629.
14. Spitzer RL, Williams JB, Kroenke K, et al.
Utility of a new procedure for diagnosing mental disor-
ders in primary care. The PRIME-MD 1000 study. JAMA
1994;272:1749-1756.
15. Sackett DL, Haynes RB, Guyatt GH, et al.
Clinical Epidemiology: A Basic Science for Clinical Med-
icine, 2nd ed. Boston: Little, Brown and Co; 1991.
16. Murphy JM, Berwick DM, Weinstein MC, et
al. Performance of screening and diagnostic tests: appli-
cation of receiver operating characteristic analysis. Arch
Gen Psychiatry 1987;44:550-555.
17. Kazis LE, Anderson JJ, Meenan RF. Effect
sizes for interpreting changes in health status. Med Care
1989;27:S178-S189.
18. Williams JW Jr, Pignone M, Ramirez G, et al.
Identifying depression in primary care: a literature syn-
thesis of case-finding instruments. Gen Hosp Psychiatry
2002;24:225-237.
19. Berwick DM, Murphy JM, Goldman PA, et
al. Performance of a five-item mental health screening
test. Med Care 1991;29:169-176.
20. Kroenke K. Depression screening is not
enough. Ann Intern Med 2001;134:418-420.
21. Valenstein M, Vijan S, Zeber JE, et al. The
cost-utility of screening for depression in primary care.
Ann Intern Med 2001;134:345-360.
22. Kroenke K, Taylor-Vaisey A, Dietrich AJ,
et al. Interventions to improve provider diagnosis and
treatment of mental disorders in primary care: a
critical review of the literature. Psychosomatics
2000;41:39-52.
23. Simon GE. Can depression be managed appro-
priately in primary care? J Clin Psychiatry 1998;59(suppl
2):3-8.
24. Oxman TE, Dietrich AJ, Williams JW, et al. A
three component model for reengineering systems for
the treatment of depression in primary care. Psychoso-
matics 2002;43:441-450.
25. Bush B, Shaw S, Cleary P, et al. Screening for
alcohol abuse using the CAGE questionnaire. Am J Med
1987;82:231-235.
1292
MEDICAL CARE
This content downloaded from 128.104.1.219 on Thu, 2 May 2013 09:14:20 AM
All use subject to JSTOR Terms and Conditions