Depression and work incapacity in Scotland: Evidence from the Scottish Health and British Household Panel Surveys

Matt Sutton

Will Whittaker

Health Methodology Research Group

(matt.sutton@manchester.ac.uk)

Background

• Part of a mixed-methods research project funded by the Chief Scientist Office of the Scottish Government Health Directorate General

• Research questions for survey analysis

– Who is likely to transit to and from Incapacity Benefit?

– Can the ‘at-risk’ individuals be identified in general practice?

– Do practices influence work incapacity?

Trends in Incapacity Benefit receipts - UK

0%

1%

2%

3%

4%

5%

6%

1991 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005 2006 2007

BHPS DWP

Trends in mental health - BHPS

0%

1%

2%

3%

4%

5%

6%

7%

8%

9%

10%

1991 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005 2006 2007

0%

5%

10%

15%

20%

25%

Depression/anxiety GHQ Caseness

Trends in mental health of IB recipients

0%

10%

20%

30%

40%

50%

60%

1991 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005 2006 2007

BHPS IB with depression BHPS IB with GHQ Caseness DWP IB Mental health condition

Who is likely to transit to and from Incapacity Benefit?

British Household Panel Survey

• Longitudinal sample, with refreshment and booster samples

• 17 waves of interviews (1991 – 2007)

• Interviews in autumn

– Current status

– Experience since 1st September of previous year

• Analysis of working-age population with interviews in consecutive years

• Analysed years of exposure:

– 32,130 inactive job status

– 114,092 active job status

– 7,964 on Incapacity Benefit

Analysis

• Probability of transit:

– From inactive job status to IB

– From active job status to IB

– Off of IB

• Multivariate logistic regression with random-effects for individuals

• Explanatory variables:

– GHQ-12 score; Other health problems; Year; Ethnicity; Educational attainment; UK region; Marital status; Age; Gender; Children

– Inactive status

– Standard Occupational Classification; Employment sector

Conditional influence of mental health on transits

0.1

1

10

1 2 3 4 5 6 7 8 9 10 11 12

GHQ-12 Score (Reference = 0)

Od

ds

-Rat

io (

log

-sca

le)

Transits from employment to IB Transits off of IB

Conditional influence of other health conditions on transits

0

0.5

1

1.5

2

2.5

3

3.5

4

Arms o

r Leg

sSigh

t

Hearin

gSkin

Chest,

Bre

athin

g

Heart

and

blood

Stom

ach,

kidn

ey

Diabet

es

Alcoho

l, dru

gs

Epilep

sy

Migr

aine

Other

Od

ds

-Rat

io (

Re

fere

nce

= N

o h

ea

lth

pro

ble

m)

Transits from employment to IB Transits off of IB

Conditional regional variations in transits

0.1

1

10

South

Eas

t

South

Wes

t

East A

nglia

East M

idlan

ds

Wes

t Midl

ands

North

Wes

t

Yorks

. & H

umbe

r

North

Eas

t

Wale

s

Scotla

nd

N. Ire

land

Region (Reference = London)

Od

ds

-Ra

tio

(lo

g-s

ca

le)

Transits from employment to IB Transits off of IB

Conditional trends in transits onto IB

0

0.5

1

1.5

2

2.5

3

3.5

1991 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005

Od

ds

-Ra

tio

(R

efe

ren

ce

= 2

00

6)

All With depression

Conditional regional variations in transits onto IB

0

1

2

3

4

5

6

South

Eas

t

South

Wes

t

East A

nglia

East M

idlan

ds

Wes

t Midl

ands

North

Wes

t

Yorks

. & H

umbe

r

North

Eas

t

Wale

s

Scotla

nd

N. Ire

land

Od

ds

-Rat

io (

Re

fere

nce

= L

on

do

n)

All With depression

Can the ‘at-risk’ individuals be identified in general practice?

Identifying those at risk

• Identify starting year of first spell of Incapacity Benefit claiming

– N = 1,758 first spells

• Calculate prevalence in preceding and proceeding years of:

– GHQ Caseness

– Frequent GP attendance (10+ per annum)

Mental health by spell period

0

5

10

15

20

25

30

35

40

45

50

-11 -10 -9 -8 -7 -6 -5 -4 -3 -2 -1 0 1 2 3 4 5 6 7 8 9 10 11

Years from start of IB spell

GH

Q C

as

en

es

s (

%)

Frequent GP attendance by spell period

0

5

10

15

20

25

30

35

40

45

50

-11 -10 -9 -8 -7 -6 -5 -4 -3 -2 -1 0 1 2 3 4 5 6 7 8 9 10 11

Years from start of IB spell

Te

n o

r m

ore

GP

vis

its

in

la

st

ye

ar

(%)

Do practices influence work incapacity?

Scottish Health Surveys

• Cross-sectional surveys in 1995, 1998 & 2003

• Subsequently linked to NHS administrative records, including registered general practice at time of survey

Missing practice code Year Total N N %

1995 7,363 3,547 48% 1998 8,305 3,061 37% 2003 10,470 1,311 13%

• We analyse the working-age population, excluding early retired

• Sample = 12,221 individuals registered with 948 general practices

Analysis

• Multivariate logistic regression with random-effects for practices

• Empty model and model with explanatory variables:

– Year

– Gender

– Age category

– Marital status

– Educational achievement

– Health region

– Area deprivation quintile

• Focus on proportion (and significance) of unexplained variance at practice level (rho)

Unconditional Conditional

Variable Prevalence rho p rho p

Long-term sick 9% 0.084 <0.001 0.039 <0.001

No degree 84% 0.065 <0.001 0.036 <0.001

LS mental illness 4% 0.053 0.015 0.000 0.495

Married 56% 0.050 <0.001 0.021 <0.001

GHQ Caseness 17% 0.014 0.018 0.000 0.488

GP visit 18% 0.000 0.488 0.000 0.488

Gender 53% 0.000 0.488 0.000 0.488

Amount of practice variation

Comparator variables

• Female

• Married and living with spouse

• Longstanding illness - mental condition

• GHQ Caseness

• GP visit in last fortnight

• Less than degree (or equivalent) educational attainment

Amount of practice variation

Unconditional Conditional

Variable Prevalence rho p rho p

Long-term sick 9% 0.084 <0.001 0.039 <0.001

No degree 84% 0.065 <0.001 0.036 <0.001

LS mental illness 4% 0.053 0.015 0.000 0.495

Married 56% 0.050 <0.001 0.021 <0.001

GHQ Caseness 17% 0.014 0.018 0.000 0.488

GP visit 18% 0.000 0.488 0.000 0.488

Gender 53% 0.000 0.488 0.000 0.488

Summary of findings

• Increasing proportion of work incapacity attributable to mental health

• Mental health significantly influences the probability of transition to and from IB – robust to other influences

• Factors influencing the probability of transition to IB are similar for individuals with depression to those for the entire population

• Increasing prevalence of GHQ Caseness in years leading up to start of IB spell – though frequent GP attendance increases more distinctly

• Significant practice variation in prevalence of work incapacity

• ..but this may reflect geographical concentrations of socioeconomic factors rather than variations in practice behaviour