Depression: Contemporary study - Kroenke 2008

Question 1

What was the aim of Kroenke study?

Answer 1

Aimed to see whether the PHQ-8 was an effective way of assessing whether a person had depression

Wanted to compare his method (using the PHQ-8) to the method used by the DSM manual which is an algorithm

Question 2

What is an algorithm?

Answer 2

An equation/formula which converts answers from an interview using the DSM into a diagnosis

Question 3

Which type of sample did Kroenke use?

Answer 3

Used a random sample to obtain participants

Telephone numbers across America - computer randomly selected people for the sample

Question 4

How many participants did Kroenke have?

Answer 4

198,678 participants

From 38 states in America

Range of ethnicities with 78% being non-Hispanic white

Question 5

How was data collected in Kroenke study?

Answer 5

PHQ-8 added to the end of the BRFSS, regular survey about general health that ran in America, for those participants who were selected in the sample

Group of trained interviewers worked together to collect that data using telephone interviews

Question 6

What were the questions in Kroenke study like?

Answer 6

Used a Likert scale:

• feeling tired or having little energy
• poor appetite or overeating

3 additional questions asked still producing numerical data, e.g.:
-how many days was you physical/mental health which includes physical/mental illness not good? (last 30 days)

Question 7

How was the data collected in Kroenke study analysed?

Answer 7

Analysed using two methods:

• algorithm (DSM)
• Look at their score on PHQ-8 and compare outcomes

Also analysed ages, gender, ethnicity and employment status

Question 8

What were the results of Kroenke’s study?

Answer 8

Of the 17,040 participants from the original sample who had a score of 10 or more on the PHQ-8, 48.7% were also diagnosed with depression using the DSM algorithm

Only 3.5% of the 17,040 didn’t have any symptoms of depression

Question 9

Who did Kroenke find to be more likely to be depressed?

Answer 9

Found depressed people were more likely to be female, non-white, unemployed, younger than 55 and less educated

Question 10

What did Kroenke conclude?

Answer 10

Concluded that his PHQ-8 was as effective at measuring depression as the algorithm used by the DSM

Question 11

What are the strengths of Kroenke’s study?

Answer 11

Population validity

Psychology in society

Reliability

Concurrent validity

Demographics

Question 12

What are the weaknesses of Kroenke’s study?

Answer 12

Generalisability

Validity

Psychology as a science

Data

Accuracy

Question 13

Why is population validity a strength of Kroenke’s study?

Answer 13

that Kroenke used a large sample of nearly 200,000 people from 38 of the 50 US states, including big cities and rural areas and even Hawaii. People from a range of age groups were interviewed (aged 18 through to 75+).

This is a strength because large number of participants means that a range of ethnicities and age groups were included meaning the sample is representative and has good population validity.

Question 14

Why is psychology in society a strength of Kroenke’s study?

Answer 14

Kroenke’s research is that the PHQ-8 can be used to arrive at an initial diagnosis of depression through a telephone interview (or an online diagnosis).

This is strength because it helps identify people who should be encouraged to visit a doctor for a more thorough diagnosis using a manual such as the DSM. This should lead to people getting an earlier diagnosis and more effective treatment for depression.

Question 15

Why is reliability a strength of Kroenke’s study?

Answer 15

the use of closed questions in the structured interviews. This made it possible to replicate the interview in the same way with each participant using a team of trained interviewers.

This is a strength because every respondent gets the same questions in the same order, marked in the same way therefore minimising any researcher effects and increasing the reliability of the findings.

Question 16

Why is concurrent validity a strength of Kroenke’s study?

Answer 16

the comparison of the PHQ-8 to the algorithm used in the DSM manual to check whether both methods of diagnosing depression are effective.

This is a strength because Kroenke was able to conclude that both techniques are effective. Having measurements from both, means he could establish concurrent validity.

Question 17

Why is demographics a strength of Kroenke’s study?

Answer 17

Kroenke analysed the data looking at the demographics of people who were more likely to be depressed, looking at socioeconomic status, gender and age.

This is a strength because it could lead to targeted support for these groups in terms of offering preventative measures such as social support or financial help in an attempt to lower rates of depression.

Question 18

Why is generalisability a weakness of Kroenke’s study?

Answer 18

many more people who were randomly selected and telephoned may have declined the call or withdrawn and refused to answer questions about their mental health.

This is a weakness because this may have included people with the most severe depression and mental health problems or people with the fewest. This would consequently lower the generalisability of the findings to such individuals.

Furthermore, those who did answer may be more helpful (volunteers), again making them less representative.

Question 19

Why is validity a weakness of Kroenke’s study?

Answer 19

asking the questions over the telephone may mean that participants give different responses to the researcher than they might have written if they filled out the PHQ themselves as a questionnaire.

This is a weakness because respondents might want to conceal health problems from a stranger and therefore give socially desirable answers. This would therefore lower the validity of the findings.

Question 20

Why is psychology as a science a weakness of Kroenke’s study?

Answer 20

the respondent might not answer on the 4-point scale as they are supposed to, but instead start describing their experiences.

This is a weakness because instead of producing quantitative data, qualitative data is collected forcing the researcher to make a subjective decision about how to score the response. This may lead to bias.

Question 21

Why is data a weakness of Kroenke’s study?

Answer 21

Kroenke collected quantitative data using a restricted scale ranging from 3 points for ‘nearly every day’ to 0 points for ‘not at all’.

This is a weakness because it fails to explain the reasons behind the respondent’s answer, therefore offering little meaning and lowering the validity of the findings.

However, the use of quantitative data is advantageous, allowing comparisons to be made easily when Kroenke analysed the demographics of the sample.

Question 22

Why is accuracy a weakness of Kroenke’s study?

Answer 22

Kroenke collected data from each participant on one particular day; asking them to reflect on how they had felt over the past two weeks.

This is a weakness because it only provides a snapshot of that person’s emotions on that day, and they may forget how they had felt over the last two weeks. This may lower the accuracy and validity of their responses.