Table 1.
Baseline characteristics of participants stratified by smoking status*
| Never (n = 248 128) | Former (n = 158 123) | Current (n = 32 259) | Overall (n = 438 510) | |
|---|---|---|---|---|
|
Age (years), mean (SD)
|
55.8 (8.17) |
57.7 (7.84) |
54.5 (8.07) |
56.4 (8.12) |
|
Sex
|
|
|
|
|
| Female |
148 343 (59.8) |
76 074 (48.1) |
16 229 (50.3) |
240 646 (54.9) |
| Male |
99 785 (40.2) |
82 049 (51.9) |
16 030 (49.7) |
197 864 (45.1) |
|
Back pain occurrence
|
|
|
|
|
| Yes |
16 166 (6.5) |
12 120 (7.7) |
3181 (9.9) |
31 467 (7.2) |
| No |
231 962 (93.5) |
146 003 (92.3) |
29 078 (90.1) |
407 043 (92.8) |
|
Ethnicity
|
|
|
|
|
| White |
231 281 (93.2) |
153 044 (96.8) |
30 407 (94.3) |
414 732 (94.6) |
| Mixed |
1316 (0.5) |
926 (0.6) |
376 (1.2) |
2618 (0.6) |
| Chinese |
1162 (0.5) |
203 (0.1) |
79 (0.2) |
1444 (0.3) |
| South Asian |
6613 (2.7) |
1422 (0.9) |
490 (1.5) |
8525 (1.9) |
| Black |
3391 (1.4) |
1052 (0.7) |
467 (1.4) |
4910 (1.1) |
| Other |
4365 (1.8) |
1476 (0.9) |
440 (1.4) |
6281 (1.4) |
|
BMI categories
|
|
|
|
|
| Underweight |
1333 (0.5) |
472 (0.3) |
455 (1.4) |
2260 (0.5) |
| Normal |
87 550 (35.3) |
43 871 (27.7) |
12 042 (37.3) |
143 463 (32.7) |
| Overweight |
103 259 (41.6) |
70 882 (44.8) |
12 854 (39.8) |
186 995 (42.6) |
| Obese |
55 986 (22.6) |
42 898 (27.1) |
6908 (21.4) |
105 792 (24.1) |
|
Educational level
|
|
|
|
|
| College |
91 042 (36.7) |
48 388 (30.6) |
6148 (19.1) |
145 578 (33.2) |
| Professional qualifications |
37 104 (15.0) |
22 792 (14.4) |
3869 (12.0) |
63 765 (14.5) |
| Others |
119 982 (48.4) |
86943 (55.0) |
22 242 (68.9) |
229 167 (52.3) |
|
Townsend deprivation index, mean (SD)
|
-1.60 (2.94) |
-1.23 (3.08) |
0.452 (3.55) |
-1.31 (3.09) |
|
Sedentary behavior, mean (SD)
|
4.62 (2.35) |
5.02 (2.44) |
5.45 (2.95) |
4.82 (2.44) |
|
Number of cigarettes smoked daily, mean (SD)
|
NA |
18.8 (9.85) |
15.4 (8.26) |
NA |
| Pack-years of own smoking, years, mean (SD) | NA | 20.7 (17.0) | 28.0 (17.3) | NA |
SD – standard deviation, BMI – body mass index, NA – not applicable
*Data are presented as n (%), unless specified otherwise.