KROENKE ET AL
Contemporary Study for disorder other than schizophrenia; 2008
This study is significant because it shows the PHQ is being given rigorous statistical analysis
to see if it scores depression accurately. It also focuses on Major Depressive Disorder (MDD)
as classified in DSM-IV-TR, and illustrates the cognitive approach, using quantitative data to
measure thoughts and beliefs. It also illustrates the power and shortcomings of mass
surveys, because nearly 200,000 participants were approached via telephone calls.
What is the PHQ-8?
Kroenke had already worked on PRIME-MD, a checklist that helped doctors make diagnoses
of mental disorders based on DSM-IV-TR. PRIME-MD contained a mood checklist for
diagnosing mood disorders like depression. Kroenke and his team adapted the PRIME-MD
into a short questionnaire that patients could fill in themselves, they made it so the
questions could be asked over the phone, this was called the PHQ-9 (because it asked 9
questions). Kroenke’s team dropped one question from the PHQ-9 for the purpose of the
study, and hence it was called the PHQ-8.
The PHQ doesn’t just indicate how severe a person’s depression is, it aims to make a fairly
accurate diagnosis of clinical depression. If the respondent scores 10 or more on PHQ, it
indicates that they have a depressive disorder. The question with this is whether a score in
excess of 10 in the PHQ is a reliable and valid way of diagnosing someone with a depressive
disorder.
Aim: To find out if PHQ-8 is a valid measure of depression, particularly to investigate
whether there is a difference between diagnosis of depression using the PHQ-8 algorithm
and using the PHQ-8 score of over 10.
IV: Whether the respondent is being classified as clinically depressed using the PHQ-8
algorithm or PHQ-8 cutpoint of over 10 as a score.
DV: The number of telephone respondents who were diagnosed with depression.
Sample: 198,678 Americans who took part in a mental health survey over the telephone in
2006. This was part of a regular survey called the Behavioural Risk Factor Surveillance
Survey (BRFSS) in the USA, it surveys into health in general, infectious diseases, asthma,
domestic violence, etc. but in 38 states questions were asked about depression using PHQ-8.
Telephone numbers were produced RANDOMLY by a computer and people who answer are
invited to take part.
Procedure: Researchers obtained data from BRFSS survey and analysed responses to these
questions. Respondents were diagnosed based on their answers, using two methods: the
depressive disorder based on PHQ algorithm OR PHQ-8 cutpoint of a score over 10 (out of
24).
In addition, three questions were asked to indicate mental health over the past 30 days.
PHYSICAL HEALTH “How many days was your physical health, which includes physical
illness or injury, not good?”
MENTAL HEALTH “How many days was your mental health, which includes stress,
depression and problems with emotions, not good?”
ACTIVITY LIMITATIONS “How many days did poor physical or mental health keep you
from doing your usual activities, such as self-care, work, or recreation?”
Finally, the team considered sociodemographic data, like age, gender, ethnicity, and
employment status.
Contemporary Study for disorder other than schizophrenia; 2008
This study is significant because it shows the PHQ is being given rigorous statistical analysis
to see if it scores depression accurately. It also focuses on Major Depressive Disorder (MDD)
as classified in DSM-IV-TR, and illustrates the cognitive approach, using quantitative data to
measure thoughts and beliefs. It also illustrates the power and shortcomings of mass
surveys, because nearly 200,000 participants were approached via telephone calls.
What is the PHQ-8?
Kroenke had already worked on PRIME-MD, a checklist that helped doctors make diagnoses
of mental disorders based on DSM-IV-TR. PRIME-MD contained a mood checklist for
diagnosing mood disorders like depression. Kroenke and his team adapted the PRIME-MD
into a short questionnaire that patients could fill in themselves, they made it so the
questions could be asked over the phone, this was called the PHQ-9 (because it asked 9
questions). Kroenke’s team dropped one question from the PHQ-9 for the purpose of the
study, and hence it was called the PHQ-8.
The PHQ doesn’t just indicate how severe a person’s depression is, it aims to make a fairly
accurate diagnosis of clinical depression. If the respondent scores 10 or more on PHQ, it
indicates that they have a depressive disorder. The question with this is whether a score in
excess of 10 in the PHQ is a reliable and valid way of diagnosing someone with a depressive
disorder.
Aim: To find out if PHQ-8 is a valid measure of depression, particularly to investigate
whether there is a difference between diagnosis of depression using the PHQ-8 algorithm
and using the PHQ-8 score of over 10.
IV: Whether the respondent is being classified as clinically depressed using the PHQ-8
algorithm or PHQ-8 cutpoint of over 10 as a score.
DV: The number of telephone respondents who were diagnosed with depression.
Sample: 198,678 Americans who took part in a mental health survey over the telephone in
2006. This was part of a regular survey called the Behavioural Risk Factor Surveillance
Survey (BRFSS) in the USA, it surveys into health in general, infectious diseases, asthma,
domestic violence, etc. but in 38 states questions were asked about depression using PHQ-8.
Telephone numbers were produced RANDOMLY by a computer and people who answer are
invited to take part.
Procedure: Researchers obtained data from BRFSS survey and analysed responses to these
questions. Respondents were diagnosed based on their answers, using two methods: the
depressive disorder based on PHQ algorithm OR PHQ-8 cutpoint of a score over 10 (out of
24).
In addition, three questions were asked to indicate mental health over the past 30 days.
PHYSICAL HEALTH “How many days was your physical health, which includes physical
illness or injury, not good?”
MENTAL HEALTH “How many days was your mental health, which includes stress,
depression and problems with emotions, not good?”
ACTIVITY LIMITATIONS “How many days did poor physical or mental health keep you
from doing your usual activities, such as self-care, work, or recreation?”
Finally, the team considered sociodemographic data, like age, gender, ethnicity, and
employment status.
