Descriptive statistics
There were 42,968 participants included in our sample, most of whom were White British (n = 35,918; 84.0%). All other ethnic groups had between 1,132 participants (Bangladeshi) and 1,905 participants (Indian). There were more females than males in our sample, which was most pronounced in among Caribbean (60.1% female), White British (56.4% female), and African (55.9% female) participants. In contrast, there was nearly equal proportions of females and males in the Bangladeshi (49.2% female) and Indian (48.7% female) participants (Table 1).
Table 1 Sample characteristics by ethnic group, 2009-10 (n= 42,968)
|
African
|
Bangladeshi
|
Caribbean
|
Indian
|
Pakistani
|
White British
|
|
n
|
%
|
n
|
%
|
n
|
%
|
n
|
%
|
n
|
%
|
n
|
%
|
Total
|
|
|
|
|
|
|
|
|
|
|
|
|
|
946
|
100.0
|
622
|
100.0
|
799
|
100.0
|
1,363
|
100.0
|
906
|
100.0
|
31,407
|
100.0
|
Sex
|
|
|
|
|
|
|
|
|
|
|
|
|
Female
|
830
|
57.7
|
557
|
49.2
|
683
|
60.1
|
927
|
48.7
|
759
|
52.8
|
20,253
|
56.4
|
Male
|
608
|
42.3
|
575
|
50.8
|
454
|
39.9
|
978
|
51.3
|
679
|
47.2
|
15,665
|
43.6
|
Age
|
|
|
|
|
|
|
|
|
|
|
|
|
Mean (SD)
|
36.2
|
12.8
|
33.8
|
12.8
|
45.8
|
16.9
|
39.5
|
15.4
|
35.9
|
14.2
|
48.4
|
18.4
|
Education
|
|
|
|
|
|
|
|
|
|
|
|
|
A levels or higher
|
876
|
60.9
|
450
|
39.8
|
448
|
39.4
|
1,158
|
60.8
|
623
|
43.3
|
13,756
|
38.3
|
GCSE or lower
|
560
|
38.9
|
680
|
60.1
|
687
|
60.4
|
745
|
39.1
|
815
|
56.7
|
22,138
|
61.6
|
Missing
|
2
|
0.1
|
2
|
0.2
|
2
|
0.2
|
2
|
0.1
|
0
|
0
|
24
|
0.1
|
British citizen
|
|
|
|
|
|
|
|
|
|
|
|
|
Yes
|
858
|
59.7
|
909
|
80.3
|
1,036
|
91.1
|
1,384
|
72.6
|
1,171
|
81.4
|
35,852
|
99.8
|
No
|
879
|
40.2
|
222
|
19.6
|
101
|
8.9
|
520
|
27.3
|
267
|
18.6
|
61
|
0.17
|
Missing
|
2
|
0.1
|
1
|
0.1
|
0
|
0
|
1
|
0.05
|
0
|
0
|
5
|
0.01
|
Urban/rural
|
|
|
|
|
|
|
|
|
|
|
|
|
Urban
|
1,430
|
99.4
|
1,126
|
99.5
|
1,131
|
99.5
|
1,876
|
98.5
|
1,433
|
99.6
|
26,648
|
74.2
|
Rural
|
8
|
0.6
|
6
|
0.5
|
6
|
0.5
|
29
|
1.5
|
5
|
0.4
|
9,270
|
25.8
|
Marital status
|
|
|
|
|
|
|
|
|
|
|
|
|
Partnered (married / cohabiting)
|
664
|
46.2
|
716
|
63.2
|
420
|
36.9
|
1,265
|
66.4
|
946
|
65.8
|
22,787
|
63.4
|
Separated / divorced / widowed
|
199
|
13.8
|
84
|
4.7
|
222
|
19.5
|
138
|
7.2
|
143
|
9.9
|
5,877
|
16.4
|
Single
|
575
|
40.0
|
331
|
29.2
|
493
|
43.4
|
502
|
26.4
|
348
|
24.2
|
7,244
|
20.2
|
Missing
|
-
|
-
|
1
|
0.1
|
2
|
0.2
|
0
|
0
|
1
|
0.1
|
10
|
0.0
|
Psychological distress
|
|
|
|
|
|
|
|
|
|
|
|
|
GHQ-12 mean score (SD)
|
1.86
|
2.81
|
2.24
|
2.94
|
2.01
|
2.95
|
1.78
|
2.85
|
2.22
|
3.19
|
1.73
|
2.87
|
n: number; SD: standard deviation; GHQ: General Health Questionnaire
[Table 1 here]
There were interesting patterns of education across the ethnic groups. In the African and Indian groups, over 60% had completed A levels or higher, with 38.9% (African) and 39.1% (Indian) leaving school with GCSE qualifications or lower. These proportions were the inverse of what was seen in the White British and Bangladeshi groups, where only 38.3% (White British) and 39.8% (Bangladeshi) had achieved post-secondary qualifications (A levels or higher).
The proportions who had British citizenship also varied greatly across ethnic groups. 99.8% of the White British group reported being a citizen of the UK. Several other ethnic groups had high proportions of citizens, including 91.1% of Caribbean participants, 81.4% of Pakistani participants, and 80.3% of Bangladeshi participants. The lowest proportion of citizenship was observed in African participants, with 59.7% reported having citizenship in the UK.
Over 99% of participants from African, Bangladeshi, Caribbean, Indian, and Pakistani groups lived in urban areas. There was a smaller proportion of the White British living in urban areas (74.2%).
Over 60% of participants in Bangladeshi, Indian, Pakistani, and White British groups were married or cohabitating. There were lower rates of marriage/cohabitation in the African (46.2%) or Caribbean (36.9%) groups.
At the start of the study, levels of psychological distress were highest in the Bangladeshi (mean GHQ: 2.24, SD: 2.94) and Pakistani (mean GHQ: 2.22, SD: 3.19) ethnic groups. The lowest levels of psychological distress were observed in the White British ethnic group (mean GHQ: 1.72, SD: 2.87) and Indian ethnic group (mean GHQ:1.78, SD: 2.85).
Difference-in-differences models: We used difference-in-difference (DiD) models to estimate the marginal mean psychological distress score for each ethnic group during the three policy eras: pre-policy era, transition era, and ongoing policy era (Table 2). Figure 1 displays the trends in psychological distress based on the marginal means from the adjusted model across the three policy eras by ethnic group. During the pre-policy era, the highest marginal mean GHQ was found in the Pakistani group, which had a marginal mean GHQ of 2.70, compared to 2.08 in the White British group. The Bangladeshi and Caribbean groups similarly had elevated GHQ scores of 2.47. The marginal mean GHQ of both the Indian and African ethnic groups in the pre-policy era were similar to the White British group, at 2.13 and 2.16, respectively.
Table 2
Psychological distress scores by ethnic group and policy period, imputed data
| PRE-POLICY PERIOD | TRANSITION PERIOD | ONGOING POLICY PERIOD |
| Coeff. | 95% CI | Coeff. | 95% CI | Coeff. | 95% CI |
African | | | | | | | | | |
Unadjusted | 1.94 | 1.57 | 2.30 | 1.59 | 0.93 | 2.24 | 1.78 | 1.06 | 2.50 |
Adjusted1 | 2.16 | 1.77 | 2.54 | 1.91 | 1.24 | 2.58 | 1.95 | 1.23 | 2.68 |
Bangladeshi | | | | | | | | | |
Unadjusted | 2.23 | 1.76 | 2.70 | 2.46 | 1.58 | 3.34 | 2.57 | 1.61 | 3.53 |
Adjusted1 | 2.47 | 2.00 | 2.94 | 2.71 | 1.85 | 3.57 | 2.80 | 1.79 | 3.82 |
Caribbean | | | | | | | | | |
Unadjusted | 2.25 | 1.84 | 2.67 | 2.18 | 1.46 | 2.90 | 2.13 | 1.38 | 2.88 |
Adjusted1 | 2.47 | 2.03 | 2.91 | 2.46 | 1.72 | 3.20 | 2.36 | 1.57 | 3.16 |
Indian | | | | | | | | | |
Unadjusted | 1.84 | 1.50 | 2.17 | 1.65 | 1.10 | 2.19 | 1.63 | 1.04 | 2.22 |
Adjusted1 | 2.13 | 1.78 | 2.48 | 1.98 | 1.41 | 2.55 | 2.02 | 1.42 | 2.62 |
Pakistani | | | | | | | | | |
Unadjusted | 2.55 | 2.11 | 2.98 | 2.64 | 1.85 | 3.42 | 2.42 | 1.58 | 3.25 |
Adjusted1 | 2.70 | 2.26 | 3.14 | 2.92 | 2.16 | 3.68 | 2.80 | 1.96 | 3.64 |
White British | | | | | | | | | |
Unadjusted | 1.85 | 1.78 | 1.91 | 1.85 | 1.74 | 1.95 | 1.87 | 1.76 | 1.98 |
Adjusted1 | 2.08 | 1.98 | 2.19 | 2.09 | 1.95 | 2.24 | 2.09 | 1.93 | 2.24 |
1Adjusted for sex, age, marital status, education, citizenship status, urban/rural status. |
[Table 2 here]
During the transition era, the marginal mean GHQ score increased for the Pakistani and Bangladeshi groups, reaching 2.92 and 2.71, respectively. The remaining ethnic groups saw their GHQ scores remain stable or decrease slightly, with the greatest decrease seen in the African group to a marginal mean GHQ score of 1.91.
Finally, in the ongoing policy era, the marginal mean GHQ score continued to rise for the Bangladeshi group, reaching 2.80. The Indian and African groups saw slight increases in their marginal mean GHQ scores, reaching 2.02 and 1.95, respectively. The marginal mean GHQ score in the Pakistani and Caribbean groups decreased to 2.80 and 2.36, respectively, while the GHQ score of the White British group remained approximately stable at 2.09. Similar patterns were found in the complete case analysis (Supplement).
[Figure 1a-e here]