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Depression and work incapacity in Scotland: Evidence from the Scottish Health and British Household Panel Surveys
Matt Sutton
Will Whittaker
Health Methodology Research Group
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