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The Patient Health Questionnaire for Adolescents

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ORIGINAL ARTICLE
The Patient Health Questionnaire for Adolescents:
Validation of an Instrument for the Assessment
of Mental Disorders Among Adolescent Primary Care Patients
JEFFREY G. JOHNSON, Ph.D., EMILY S. HARRIS, M.D., ROBERT L. SPITZER, M.D., AND
JANET B. W. WILLIAMS, D.S.W.
Purpose: To investigate the validity of the Patient
Health Questionnaire for Adolescents (PHQ-A), a self-
administered instrument that assesses anxiety, eating,
mood, and substance use disorders among adolescent
primary care patients.
Methods: A total of 403 adolescents from California,
New Jersey, New York, and Ohio completed the PHQ-A
and the Medical Outcomes Study Short-Form General
Health Survey (SF-20) during or shortly after a visit to a
primary care clinic or a school nurse’s office. A few days
later, clinical psychologists who were blind to the results
of the PHQ-A administered a semi-structured clinical
interview to assess the same psychiatric disorders and to
conduct a global assessment of functioning (GAF) among
403 patients. Diagnostic agreement coefficients were
computed and analyses of covariance were conducted.
Results: Findings support the diagnostic validity of the
PHQ-A. The PHQ-A and the clinical interview produced
similar estimates of the prevalence rates of anxiety,
eating, mood, and substance use disorders. The PHQ-A
demonstrated satisfactory sensitivity, specificity, diag-
nostic agreement, and overall diagnostic accuracy, com-
pared with the clinical interview. Adolescents with
PHQ-A diagnoses experienced significantly poorer men-
tal and overall functioning, more physical pain, and
poorer overall health compared with those without psy-
chiatric disorders. These differences remained signifi-
cant after patients’ age, gender, ethnicity, and site were
controlled statistically.
Conclusion: The PHQ-A may be used to assist primary
care practitioners in identifying psychiatric disorders
among their adolescent patients. The PHQ-A is the first
such tool to be tested for use in adolescents and offers an
acceptable and efficient tool for early detection and
recognition of mental disorders in this high-risk group.
? Society for Adolescent Medicine, 2002
Mental disorders are common among adolescents
[1] and are associated with impairment, distress,
morbidity, mortality, and chronicity [2,3]. Adoles-
cents with major depression, one of the most preva-
lent psychiatric disorders in this age group, are at
elevated risk for subsequent anxiety, mood, and
substance use disorders [4–6], disruption of aca-
demic and social development, and attempted or
completed suicide. Recent studies document that
even those adolescents with psychiatric symptoms
that do not meet diagnostic criteria are at risk for
psychosocial impairment and future psychiatric
morbidity [7,8]. In the majority of cases, a mental
disorder in adolescence precedes the onset or recur-
rence of psychiatric disorders during adulthood [9].
Early detection and intervention of mental disorders
during adolescence can have an important impact on
adult mental health outcomes [10].
Although many youths with emotional and be-
havioral problems visit primary care practitioners,
few are treated by mental health professionals [11].
From the Department of Psychiatry, Columbia University and the
New York State Psychiatric Institute, New York, New York (J.G.J.,
R.L.S., J.B.W.W.); and the Department of Psychiatry and the Center for
Health Services Research in Primary Care, University of California,
Davis, California (E.S.H.).
Address correspondence to: Jeffrey G. Johnson, Ph.D., Box 60, New
York State Psychiatric Institute, 1051 Riverside Drive, New York, NY
10032. E-mail: jjohnso@pi.cpmc.columbia.edu
Manuscript accepted August 13, 2001.
JOURNAL OF ADOLESCENT HEALTH 2002;30:196–204
? Society for Adolescent Medicine, 2002
Published by Elsevier Science Inc., 655 Avenue of the Americas, New York, NY 10010
1054-139X/02/$–see front matter
PII S1054-139X(01)00333-0

Similar patterns have been observed among adult
primary care patients, and these have been a focus of
research and intervention for the past decade. Mental
disorders are among the most common disorders
seen among adult primary care patients [12,13] and
these patients experience substantial impairment,
distress, and health care costs [14,15]. Most adult
patients with mental disorders seek treatment from
primary care physicians rather than from mental
health professionals [16]; however, most mental dis-
orders among these patients are not recognized by
their primary care physicians [17] resulting in inad-
equate or inappropriate treatment. Research has sim-
ilarly revealed that most mental disorders among
children and adolescents are not recognized by pri-
mary care physicians [18,19]. Case identification is
essential in order to ensure early treatment and
prevention of secondary morbidity.
To improve the recognition of mental disorders by
primary care physicians, Primary Care Evaluation of
Mental Disorders (PRIME-MD), a two-stage diagnos-
tic system including a screening questionnaire and a
clinical interview, was developed for use by primary
care physicians [20]. Two of the principal co-devel-
opers of the PRIME-MD (R.L.S., J.B.W.) are co-
authors of the present report. More recently, a self-
administered version of this instrument, the
PRIME-MD Patient Health Questionnaire (PHQ) was
developed and has been found to accurately and
reliably diagnose mental disorders among primary
care patients [21]. However, the PHQ has not been
validated in an adolescent population. In addition,
the PHQ does not assess dysthymic disorder, gener-
alized anxiety disorder, or drug abuse/dependence,
disorders that are relatively common among adoles-
cents in the community [22,23]. Therefore, an ex-
panded version of the PHQ, the Patient Health
Questionnaire for Adolescents (PHQ-A) was devel-
oped for the assessment of mental disorders among
adolescent primary care patients [24].
Development of the PHQ-A
The two components of the original PRIME-MD (the
patient questionnaire and the clinical evaluation
guide) were combined into a 6-page, 67-item ques-
tionnaire that can be entirely self-administered by
the patient in 5 minutes or less. The clinician scans
the completed questionnaire and applies diagnostic
algorithms that are printed in abbreviated form at
the bottom of each page. In this study, the data from
the PHQ-A were entered into a computer program
that applied the diagnostic algorithms (written using
the Statistical Package for the Social Sciences [SPSS
Inc., Chicago, IL]).
The PHQ-A was developed to assess generalized
anxiety disorder (GAD, also referred to as overanx-
ious disorder of childhood), panic disorder; bulimia
nervosa (BN); major depressive disorder (MDD),
dysthymic disorder; and substance use disorders
including alcohol, cocaine, hallucinogen, inhalant,
marijuana, opiate, sedative, and stimulant abuse or
dependence. Like the original PRIME-MD, these
disorders are divided into two groups. Threshold
disorders (BN, GAD, MDD, dysthymic disorder, and
panic disorder) for which symptoms meet the Fourth
Edition of the Diagnostic and Statistical Manual of
Mental Disorders (DSM-IV) criteria for diagnosis and
subthreshold disorders (alcohol abuse or depen-
dence, drug abuse or dependence) for which fewer
symptoms are assessed than are required for any
specific DSM-IV diagnosis [26].
Impairment for those who had endorsed any
problem was assessed by an item at the end of the
PHQ-A: “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?” Evidence of impair-
ment, assessed with this item, was required for the
diagnosis of an anxiety, eating, or mood disorder.
Specific forms of impairment associated with sub-
stance abuse or dependence were assessed by items
specific to those areas. As with the original PRIME-
MD, the physician is expected to rule out physical
causes of anxiety and depression and normal be-
reavement or history of a manic episode before
making a diagnosis of depression.
Research Questions
The present study investigated the validity of the
PHQ-A in a multisite sample of adolescent patients
in a range of primary care settings, by focusing on
the following questions: (a) “Are diagnoses made
with the PHQ-A as accurate as diagnoses made with
the original PRIME-MD interview, using indepen-
dent diagnoses made by mental health professionals
(MHPs) as the criterion standard?”; (b) “Is the prev-
alence of mental disorders identified using the
PHQ-A comparable to that obtained from MHP
interviews, and to that obtained in other primary
care studies?”; and (c) “Is the construct validity of the
PHQ-A comparable to the original PRIME-MD inter-
view with regard to impaired functioning, distress,
and poor overall health?”
March 2002 VALIDATION OF THE PHQ-A 197

Methods
Sample
The sample consisted of 403 English-speaking ado-
lescent primary care patients (36.7% male, 63.3%
female) between the ages of 13 and 18 years (mean
age � 15.90 years, SD �1.24) who showed no evi-
dence of mental retardation or organic mental disor-
der and had at least 9 years of education. The
composition of the sample was 77.2% white, 4.2%
African-American, 12.4% Hispanic, 2.2% Asian or
Pacific Islander, 1.5% Native American and 2.2%
Other. A total of 254 participants were recruited from
the greater Sacramento and Northern California re-
gion through the University of California Davis
Health System Primary Care Network (PCN) with
offices in rural, suburban and urban locations and
providing care to an ethnically diverse patient pop-
ulation. Complete data sets were obtained from 241
of these youths. A total of 404 participants were
randomly recruited from primary care and school
nurse offices in Ohio, New Jersey and New York:
Columbia Presbyterian Medical Center Adolescent
Medical Clinic, NY (n � 37); Staten Island Hospital
Adolescent Medical Clinic, NY (n� 114); Monmouth
County Medical Center, NJ (n � 7); family practice
office, Monmouth, NJ (n � 8); Keyport High School,
Keyport, NJ (n � 120); St. Mary’s Regional High
School, South Amboy, NJ (N� 13); First Care Family
Health and Immediate Care Center, Akron, OH (n �
9) and Green High School, Green, OH (n � 96).
Complete data sets were obtained from 403 of these
youths, but the present analyses were conducted
with 162 of these participants, as described below.
Parents of those less than age 18 years and partici-
pants over age 18 years provided written informed
consent, and youths under age 18 years provided
written informed assent after having read a detailed
description of the study procedures. Study proce-
dures were approved by the Institutional Review
Boards in accordance with review procedures at
New York State Psychiatric Institute, Columbia-Pres-
byterian Medical Center, and the University of Cal-
ifornia Davis School of Medicine.
Validation Measures
Clinical validation interview. To determine the di-
agnostic agreement between the PHQ-A and the
assessment of a mental health professional (MHP), a
Ph.D.-level clinical psychologist conducted a tele-
phone interview with each participant who com-
pleted and returned the PHQ-A by mail and could be
contacted by telephone. The MHPs, who were blind
to the results of the PHQ-A, administered a semi-
structured clinical validation interview, which in-
cluded items from the Structured Clinical Interview
for DSM-III-R (SCID) [25]), the PRIME-MD Clinical
Evaluation Guide (CEG) [20], and the DSM-IV
Global Assessment of Functioning (GAF) [26]. The
validation interview was identical in most respects to
the validation interview that was administered in the
original PRIME-MD 1000 validation study. Semi-
structured interview items from the SCID were used
to assist the interviewer in developing a broad clin-
ical impression of the youth, while items from the
PRIME-MD Clinical Evaluation Guide were used to
assess specific diagnostic criteria. Data were not
collected with regard to the validity of the clinical
validation interview itself. However, because the
interviewers were trained mental health profession-
als, and because they used information from both
SCID items and the PRIME-MD Clinical Evaluation
Guide in conducting their assessments, it is likely
that the validity of the clinical validation interview is
somewhat greater than that of the standard
PRIME-MD interview as administered by a primary
care physician. GAF ratings are made on a 100-point
scale. The items from the PRIME-MD CEGwere used
to assess specific symptoms of anxiety, depressive,
eating, and substance use disorders corresponding
with those assessed by the PHQ-A. A high GAF
rating indicates a high current level of overall func-
tioning and a low current level of psychopathology.
A GAF rating of 50 or lower is indicative of poor
overall functioning and/or severe psychopathology.
The telephone interview began with several open-
ended questions from the SCID regarding the pa-
tient’s overall functioning, mood, recent stressful life
events, and family or work problems to reveal psy-
chopathology that might not be elicited by the more
structured CEG. As in the standard administration of
the SCID, the MHP was specifically encouraged to
explore any ambiguous responses. The items from
the CEG were administered to assess the specific
anxiety, eating, mood, and substance use disorders
that are assessed by the PHQ-A. Items from the
alcohol abuse or dependence module of the CEG
were modified to assess drug abuse or dependence.
After completing the telephone interview, the MHPs
conducted an assessment of the patient’s overall
level of functioning using the GAF. Telephone inter-
views were used because of their convenience and
demonstrated comparability with face-to-face re-
search interviews [27,28].
198 JOHNSON ET AL. JOURNAL OF ADOLESCENT HEALTH Vol. 30, No. 3

The Medical Outcomes Study Short Form General
Health Survey (SF-20). The SF-20 [29] is a 20-item
self-report questionnaire which assesses six dimen-
sions of health-related quality of life (physical, social,
and role functioning, mental health, bodily pain, and
general health perceptions). Scores on all six SF-20
scales range from 0 to 100, with higher scores indi-
cating better health and less functional impairment.
A 5-point reduction in SF-20 scale scores is generally
considered clinically significant. Research has pro-
vided considerable support for the reliability and
validity of the SF-20 [30–32].
Procedures
California sample. Adolescents with a recent pri-
mary care office visit within the Primary Care Net-
work were identified using appointment records
available through a centralized practice management
system. Records were reviewed on a regular basis
between November 1997 and June 1998. Letters de-
scribing the study and requesting written consent
were sent to parents/guardians of all adolescents. In
response to over 900 letters, parental consent was
returned for 285 adolescents (32%); assent forms and
self-report measures were then sent directly to the
adolescent by mail. Of those, 254 adolescents (89%)
completed and returned the questionnaires and con-
sent. MHPs conducted telephone interviews with 241
of those subjects (95%) within a 1-week time frame.
After the clinical interview was completed, each
participant was mailed a payment of $20.00.
New York, New Jersey, and Ohio samples. Adoles-
cent patients were informed by their physicians,
between December 1995 and May 1997 of the oppor-
tunity to participate in the present study. The pa-
tients who chose to participate were provided with a
packet including informed consent forms, the
PHQ-A, and the SF-20. After completing these forms,
442 youths mailed them to the investigators in a
stamped, self-addressed envelope that was included
in the packet. When each questionnaire packet was
received by mail, the participant’s telephone number
was provided to a MHP. The MHP attempted to
conduct a clinical interview with the patient as soon
as the patient could be contacted by telephone. An
original sample of 442 patients completed the
PHQ-A and SF-20 and returned them by mail. The
MHPs succeeded in conducting interviews with 403
of these patients (91%). However, owing to schedul-
ing difficulties, most of these interviews were con-
ducted more than 2 weeks after the adolescents had
completed the PHQ-A and the SF-20. Because diag-
nostic agreement tends to decline as the length of the
inter-test interval increases [33], patients who were
interviewed more than 18 days after they completed
the PHQ-A were excluded from the present sample.
The mean interval between the completion of the
PHQ-A and the administration of the clinical inter-
view among the 162 patients from the NJ, NY, and
OH sites who were interviewed within 18 days of the
completion of the PHQ-A was 11.11 days (SD�4.16).
After the clinical interview was administered by the
MHP, each participant was mailed a payment of
$25.00.
Results
Diagnostic Results of PHQ-A Evaluations
As Table 1 indicates, 20.8% of the participants were
Table 1. Prevalence of Psychiatric Disorders Among 403 Adolescent Primary Care Patients, Diagnosed Using the
PRIME-MD PHQ-A and the PRIME-MD Clinical Interview
a
Psychiatric Disorder PRIME-MD PHQ-A % (n/N) Clinical Interview
a
%(n/N)
Any psychiatric disorder 20.8 (84/403) 19.6 (79/403)
Any anxiety disorder 4.2 (17/403) 5.0 (20/403)
Panic disorder 2.0 (8/403) 3.0 (12/403)
Generalized anxiety disorder 3.5 (14/403) 2.5 (10/403)
Any mood disorder 14.4 (58/403) 11.9 (48/403)
Major depressive disorder 12.4 (50/403) 9.4 (38/403)
Dysthymic disorder 8.7 (35/403) 7.2 (29/403)
Bulimia nervosa 1.0 (4/403) 0.7 (3/403)
Any substance abuse or dependence 8.9 (36/403) 7.2 (29/403)
Probable alcohol abuse or dependence 4.0 (16/403) 4.0 (16/403)
Probable drug abuse or dependence 7.7 (31/403) 5.0 (20/403)
a
Administered by trained mental health professionals.
PHQ-A � Patient Health Questionnaire for Adolescents; PRIME-MD � Primary Care Evaluation of Mental Disorders.
March 2002 VALIDATION OF THE PHQ-A 199

diagnosed with psychiatric disorders using the
PHQ-A, while 19.6% of the participants were diag-
nosed with psychiatric disorders by the mental
health professionals. Thirty-three patients (8.2%)
were diagnosed with one psychiatric disorder, while
51 (12.7%) were diagnosed with two or more disor-
ders. There were 16 co-occurring anxiety and depres-
sive disorders, 12 co-occurring depressive and sub-
stance use disorders, 3 cases with depressive
disorders that co-occurred with bulimia nervosa, 2
cases with anxiety disorders that co-occurred with
bulimia nervosa, and one case with an anxiety dis-
order that co-occurred with a substance use disorder.
Anxiety disorders were significantly more prevalent
among participants of Hispanic origin than among
those of other ethnic backgrounds. Depressive disor-
ders were significantly more prevalent among fe-
males than among males.
The findings in Table 1 indicate that the PHQ-A
does not systematically over- or under-diagnose the
psychiatric disorders that are assessed with this
instrument. Analyses of contingency tables indicated
that the prevalence of psychiatric disorders was
somewhat lower among participants who were re-
cruited from their high school nurses’ offices (14.9%)
than among those who were recruited from primary
care clinics or physicians’ offices (22.5%). However,
this difference was not statistically significant (�
2

2.34; df � 1; p �. 05).
Diagnostic Agreement of PHQ-A With Clinical
Interviews by Mental Health Professionals
The operating characteristics of the PHQ-A are gen-
erally satisfactory and comparable to those obtained
in the PRIME-MD 1000 and PHQ Primary Care
studies (Table 2). Both the specificity (i.e., the per-
centage of cases without psychiatric disorders that
were correctly identified) and overall accuracy (i.e.,
the percentage of cases with and without disorders
that were correctly identified) of the PHQ-A were
acceptable, and both were similar to those reported
for the PHQ and original PRIME-MD clinical inter-
view [20,21]. There was moderate diagnostic agree-
ment between PHQ-A diagnoses and diagnoses by
the mental health professionals [34]. The generally
moderate sensitivity (i.e., the percentage of cases
with psychiatric disorders that were correctly iden-
tified) and diagnostic agreement between the PHQ-A
and the assessment of the mental health profession-
als tended to be similar to, but somewhat lower than
those of the PHQ and original PRIME-MD clinical
interview [20,21].
Findings regarding the positive and negative pre-
dictive power of the PHQ-A are presented in Table 3.
The PHQ-A demonstrated high negative predictive
power for each diagnostic category, indicating that
very few adolescents who were not identified as
having a mental disorder by the PHQ-A were diag-
Table 2. Operating Characteristics of the Self-Administered PRIME-MD PHQ-A Adolescent Version (N � 403), the
PRIME-MD PHQ Adult Version (N � 585),
a
and the Original Clinician-Administered PRIME-MD (N � 431)
b
*
Sensitivity
(%)
Specificity
(%)
Overall Accuracy
(%)
Diagnostic Agreement
(�)
PHQ-
A
c
PHQ
d
Original
PRIME-
MD
d
PHQ-
A
c
PHQ
d
Original
PRIME-
MD
d
PHQ-
A
c
PHQ
d
Original
PRIME-
MD
d
PHQ-
A
c
PHQ
d
Original
PRIME-
MD
d
Any psychiatric disorder 75 75 83 92 90 88 89 85 86 0.65 0.65 0.71
Any anxiety disorder 50 63 69 98 97 90 96 91 86 0.52 0.65 0.55
Panic disorder 42 81 57 99 99 99 98 98 96 0.49 0.84 0.60
Generalized anxiety disorder 50 — 57 98 — 97 97 — 94 0.40 — 0.52
Any mood disorder 75 61 67 94 94 92 92 88 84 0.63 0.58 0.61
Major depressive disorder 73 73 57 94 98 94 92 93 92 0.59 0.54 0.61
Dysthymic disorder 55 — 51 95 — 96 92 — 92 0.46 — 0.49
Bulimia nervosa 67 89 73 99 96 99 99 96 98 0.57 0.61 0.73
Any substance abuse or dependence 66 ——95 ——93 ——0.55 ——
Probable alcohol abuse or dependence 56 62 81 98 97 98 97 95 98 0.54 0.60 0.71
Probable drug abuse or dependence 70 ——96 ——94 ——0.52 ——
a
Data reported by Spitzer et al. (1999).
b
Data reported by Spitzer et al. (1994).
c
The mean inter-assessment interval was 6.6 days (SD � 4.6).
d
The maximum inter-test interval was 2 days.
*
All data are reported using mental health professionals’ diagnoses as the criterion standard.
PHQ � Patient Health Questionnaire (Adult Version); PHQ-A � Patient Health Questionnaire (Adolescent Version); PRIME-MD �
Primary Care Evaluation of Mental Disorders.
200 JOHNSON ET AL. JOURNAL OF ADOLESCENT HEALTH Vol. 30, No. 3

nosed with a mental disorder by the MHP. The
positive predictive power of the PHQ-A was moder-
ate. Overall, most (70%) of the adolescents who were
identified as having a mental disorder by the PHQ-A
were diagnosed with a mental disorder by the MHP.
However, 30% of those who were identified as
having a mental disorder by the PHQ-A were not
diagnosed with a mental disorder by the MHP. More
than half of the adolescents who were identified as
having dysthymic disorder, GAD, or probable drug
abuse or dependence by the PHQ-A were not diag-
nosed with these mental disorders by the MHP.
To investigate the possibility that different find-
ings would be obtained as a function of site, analyses
were conducted separately in the subsamples from
California (N � 241) and New Jersey, New York or
Ohio (N � 162). Similar findings were obtained with
regard to diagnostic agreement between the PHQ-A
and the clinical validation interview in the two
subsamples. Overall diagnostic agreement coeffi-
cients of��0.66 and��0.65 were obtained in these
two subsamples. Overall diagnostic agreement coef-
ficients of ��0.74 and ��0.61 were obtained in the
male and female subsamples, respectively. Overall
diagnostic agreement coefficients of��0.62 and��
0.77 were obtained in the white and nonwhite sub-
samples, respectively.
Relationship of PHQ-A Diagnoses With
Functional Status, Distress, and Impairment
Figure 1 presents findings regarding the functional
status, distress, and impairment of patients with no
PHQ-A symptoms, compared with patients who
screened positive for psychiatric symptoms but were
not diagnosed, patients with subthreshold disorders,
and patients with threshold disorders. Patients with
no psychiatric disorders had a higher level of func-
tioning on all 6 SF-20 scales than patients with
Table 3. Predictive Power of the PHQ-A, Compared With Clinical Interview Administered by a Mental
Health Professional
No PHQ-A Psychiatric Diagnosis
Psychiatric Disorder Diagnosed Using
PHQ-A
% of Cases
Undiagnosed by
Clinical Interview
a
% of Cases
Diagnosed by
Clinical Interview
% of Cases
Undiagnosed by
Clinical Interview
% of Cases
Diagnosed by
Clinical Interview
b
Any psychiatric disorder 94 6 30 70
Any anxiety disorder 97 3 41 59
Panic disorder 98 2 38 62
Generalized anxiety disorder 99 1 64 36
Any mood disorder 96 4 38 62
Major depressive disorder 97 3 44 56
Dysthymic disorder 96 4 54 46
Bulimia nervosa 100 0 50 50
Any substance abuse or dependence 97 3 47 53
Probable alcohol abuse or dependence 98 2 43 56
Probable drug abuse or dependence 98 2 55 45
a
Negative predictive power.
b
Positive predictive power.
PHQ-A � Patient Health Questionnaire for Adolescents.
Figure 1. Relationship of Primary Care Evaluation of Mental Disorders
(PRIME-MD) Patient Health Questionnaire for Adolescents (PHQ-A)
Results to Functinal Status, Distress, and Impairment. Note: Patients
with threshold disorders had significantly lower scores than patients
without any psychiatric symptoms on all six Medical Outcomes Study
Short-Form General Health Survey (SF-20) scales; they also had signif-
icantly lower scores than patients who only screened positive for
psychiatric symptoms on every scale except the physical functioning
scale. Patients with subthreshold disorders had significantly lower scores
than patients without any psychiatric symptoms on the SF-20 mental
health, physcial pain, and overall health perception scales; they also had
significantly lower scores on these three scales than patients who only
screened positive for psychiatric symptoms.
March 2002 VALIDATION OF THE PHQ-A 201

PHQ-A disorders. Analyses of covariance (ANCO-
VAs) indicated that the scores of the four groups on
each of the 6 SF-20 scales were significantly different
after patients’ age, sex, ethnicity, and site were
controlled statistically. Post-hoc tests indicated that
patients with threshold disorders had significantly
lower scores than patients without any psychiatric
symptoms and patients who screened positive for
psychiatric symptoms but had no psychiatric diag-
noses on all 6 SF-20 scales. Patients with subthresh-
old substance use disorders had significantly lower
scores than patients without any psychiatric symp-
toms on the SF-20 mental health, physical pain, and
overall health perception scales; they also had signif-
icantly lower scores on these three scales than pa-
tients who screened positive for psychiatric symp-
toms but were not diagnosed.
An ANCOVA also indicated that the four groups
differed significantly with regard to their clinician-
rated global functioning after patients’ age, sex,
ethnicity, and site were controlled statistically. (F �
62.26; df � 3, 399; p � .001). Post-hoc tests indicated
that the GAF scores of patients with threshold disor-
ders (mean � 61.82; SD � 10.95) were significantly
lower than those of patients without psychiatric
symptoms (mean � 81.98; SD � 8.69), of patients
who screened positive for psychiatric symptoms
(mean � 76.92; SD � 10.20), and of patients with
subthreshold disorders (mean � 69.69; SD � 11.97).
Patients with subthreshold disorders had signifi-
cantly lower GAF scores than patients without any
psychiatric symptoms, and their GAF scores were
also lower than those of patients who screened
positive for psychiatric symptoms but were not di-
agnosed.
Discussion
The present findings indicate that the diagnostic
validity of the PHQ-A is comparable to that of the
original PRIME-MD interview and the adult PHQ.
The diagnostic validity of the PHQ-A was demon-
strated by agreement with an independent interview
by a mental health professional (criterion validity)
and by the association of PHQ-A diagnoses with
indices of impaired functioning, distress, and poor
health (construct validity). Compared with the find-
ings of the MHP interview, the PHQ-A demon-
strated satisfactory specificity, sensitivity, diagnostic
agreement, and overall diagnostic accuracy (i.e.,
combined positive and negative predictive power;
see column 3 in Table 2). Although the diagnostic
agreement of the PHQ-A with the MHP interview
was moderate (see column 4 in Table 2), it approxi-
mates the levels of agreement among MHPs them-
selves using diagnostic interview schedules [35].
Similarly, although the sensitivities of the PHQ-A
diagnoses were modest using the interview diag-
noses as the standard, the sensitivities were compa-
rable to values obtained in a study of the sensitivity
and specificity of the Diagnostic Interview Schedule
[36]. Our findings regarding the overall diagnostic
accuracy of the PHQ-A indicates that the self-report
instrument correctly identified the vast majority of
cases that were identified by the MHP interview as
having or not having a psychiatric disorder. Our
findings indicate that the PHQ-A may assist primary
care physicians in the identification of anxiety, eat-
ing, mood, and substance use disorders among ado-
lescent patients.
The adult PHQ-A has been recommended for
administration to all new patients, patients in whom
a psychiatric diagnosis is suspected, and established
patients on a periodic basis (e.g., annually), as is
done with other screening procedures [21]. Given the
similarities between the PHQ and the PHQ-A, the
same guidelines may be used for the administration
of the PHQ-A to adolescent primary care patients.
The most important advantage of following these
recommendations is that it may be possible to alle-
viate a considerable amount of suffering among
adolescent primary care patients by identifying and
treating mental disorders in this population. How-
ever, it is important to recognize that some disad-
vantages, such as labeling, stigmatization, and pro-
vision of inappropriate or excessive treatment can
also be associated with routine administration of
screening instruments to adolescents [37]. Therefore,
it is recommended that patients who are diagnosed
with mental disorders by the PHQ-A should be
asked follow-up questions by the physician in order
to determine whether the psychiatric symptoms and
associated impairment or distress are severe enough
to merit treatment.
The PHQ-A is the first instrument of its kind to be
tested in the adolescent population. It has several
advantages over the original PRIME-MD interview
or the adult PHQ for use with adolescents in primary
care. Most importantly, the PHQ-A was designed to
assess disorders that are likely to be present among
adolescent primary care patients and it has been
validated in an adolescent population. In addition,
the PHQ-A assesses GAD, dysthymic disorder and
drug abuse/dependence, disorders which are rela-
tively common disorders among adolescents in the
202 JOHNSON ET AL. JOURNAL OF ADOLESCENT HEALTH Vol. 30, No. 3

community [27,28]. These disorders are not included
in the adult PHQ and only the first two are included
in the original PRIME-MD interview. Like the adult
PHQ, the PHQ-A has the advantage of being entirely
self-administered in less than five minutes.
The PHQ-A also has several advantages over
other instruments that may be used in the pediatric
population. The PHQ-A is the first instrument that
has been developed and validated for the specific
purpose of assessing and diagnosing anxiety, eating,
mood, and substance use disorders among adoles-
cent primary care patients. Other screening instru-
ments used in pediatric primary care settings for the
assessment of psychosocial or psychiatric morbidity
in children and adolescents either assess a single
type of psychopathology, psychosocial dysfunction,
or general psychiatric symptoms [38–41]. In addi-
tion, screening scales only suggest the possible pres-
ence of a mental disorder, and the physician is not
provided with the information necessary to diagnose
a disorder. An advantage of the PHQ-A over such
screening instruments is that, by providing the phy-
sician with clear evidence that the patient is likely to
have a current psychiatric disorder, the PHQ-A
yields findings that can be readily interpreted. In
contrast, the clinical significance of a dimensional
symptom index may not be immediately apparent.
The limitations of the present study merit consid-
eration. The present study did not assess the health
care utilization of patients with PHQ-A diagnoses or
the effects of PHQ-A findings on physicians’ recog-
nition and treatment of psychiatric disorders. The
PHQ-A was scored with a computer program to
ensure that the diagnostic algorithms were applied
correctly. The present study does not indicate how
much training is necessary in different primary care
settings to ensure that the diagnostic algorithms are
applied correctly. Because less than one-third of the
parents from the California sites who were contacted
permitted their offspring to participate, there is some
concern about the generalizability of the findings.
However, one of the strengths of the present study
with respect to generalizability is that the sample
was obtained from a variety of geographically di-
verse locations.
The present study complements the PHQ Primary
Care Study [21] and indicates that a self-adminis-
tered diagnostic questionnaire can assist primary
care physicians in diagnosing psychiatric disorders
from adolescence through adulthood. The PHQ-A is
the first such tool to be tested for use with adoles-
cents, and it is an efficient and helpful tool for the
early detection and recognition of mental disorders
in this high-risk group. Further research regarding
the management of adolescent mental disorders in
primary care settings will play an important role in
improving the effectiveness of early detection and
treatment, and thereby reducing the likelihood that
adolescents with mental disorders will develop
chronic or recurring psychiatric conditions that per-
sist into adulthood.
This research was supported by a grant from the Aaron Diamond
Foundation to Jeffrey G. Johnson, Ph.D. and grants from the
Hibbard E. Williams Research Fund, University of California,
Davis School of Medicine to Emily S. Harris, M.D. The develop-
ment of the PHQ was underwritten by an educational grant from
Pfizer US Pharmaceuticals, Inc., New York, NY. PRIME-MD is a
trademark of Pfizer Inc. Copyright held by Pfizer Inc.
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