Baseline characteristics of the Tromsø Study population, by grip strength fifths (gender and age specific)
| N | Total | 1 (Lowest grip) | 2 | 3 | 4 | 5 (Highest grip) | Trend* | |
|---|---|---|---|---|---|---|---|---|
| Men | ||||||||
| Number of participants | 2858 | 2858 | 593 | 562 | 627 | 514 | 562 | |
| Number of deaths | 1253 | 1253 | 317 | 258 | 266 | 214 | 198 | |
| Mortality rate (95% CI)† | 2858 | 38.6 (30.7 to 34.3) | 43.6 (39.1 to 48.7) | 34.4 (30.4 to 38.8) | 31.1 (27.6 to 35.1) | 30.1 (26.3 to 34.4) | 24.4 (21.2 to 28.0) | <0.001‡ |
| Age | 2858 | 62.0 (6.4) | 63.3 (6.4) | 63.0 (6.0) | 62.4 (6.3) | 62.8 (6.5) | 62.0 (6.6) | 0.001 |
| Grip strength (kPa) | 2858 | 0.84 (0.21) | 0.58 (0.12) | 0.74 (0.08) | 0.85 (0.09) | 0.95 (0.10) | 1.12 (0.15) | <0.001 |
| BMI (kg/m2) | 2855 | 26.1 (3.4) | 25.5 (3.7) | 25.7 (3.4) | 26.2 (3.2) | 26.1 (3.1) | 26.9 (3.3) | <0.001 |
| Height (cm) | 2855 | 174.8 (6.0) | 172.4 (6.8) | 174.0 (6.9) | 174.7 (6.4) | 176.0 (6.5) | 177.2 (6.0) | <0.001 |
| Systolic BP (mm Hg) | 2857 | 146.7 (20.8) | 146.0 (21.1) | 145.2 (20.7) | 147.5 (21.0) | 146.1 (20.3) | 148.7 (20.9) | 0.019 |
| Cholesterol (mmol/L) | 2851 | 6.6 (1.2) | 6.6 (1.2) | 6.7 (1.2) | 6.6 (1.2) | 6.5 (1.1) | 6.6 (1.2) | 0.475 |
| Triglycerides (mmol/L) | 2847 | 1.8 (1.1) | 1.7 (1.1) | 1.8 (1.0) | 1.8 (1.2) | 1.7 (0.9) | 1.9 (1.1) | 0.158 |
| Poor/not good health, % | 2854 | 43 | 52 | 46 | 40 | 43 | 35 | <0.001 |
| History of heart attack, % | 2848 | 10 | 10 | 11 | 10 | 13 | 6 | 0.006 |
| History of angina, % | 2847 | 12 | 16 | 13 | 11 | 12 | 9 | 0.017 |
| History of stroke, % | 2846 | 3 | 6 | 3 | 2 | 4 | 2 | <0.001 |
| History of asthma, % | 2846 | 7 | 7 | 9 | 7 | 7 | 7 | 0.614 |
| History of diabetes, % | 2846 | 4 | 5 | 2 | 4 | 4 | 3 | 0.068 |
| Blood pressure medication, % | 2841 | 20 | 21 | 18 | 21 | 21 | 17 | 0.313 |
| Smoke cigarettes, % | 2857 | 31 | 35 | 36 | 33 | 29 | 24 | <0.001 |
| No light physical activity, % | 2841 | 26 | 29 | 28 | 23 | 24 | 23 | 0.034 |
| No hard physical activity, % | 2827 | 73 | 80 | 74 | 68 | 74 | 71 | <0.001 |
| Low education, % | 2847 | 48 | 57 | 50 | 49 | 44 | 38 | <0.001 |
| Women | ||||||||
| Number of participants | 3992 | 3992 | 843 | 880 | 732 | 787 | 750 | |
| Number of deaths | 1085 | 1085 | 281 | 268 | 181 | 180 | 175 | |
| Mortality rate (95% CI)† | 3992 | 18.0 (16.9 to 19.1) | 22.8 (20.3 to 25.6) | 20.4 (18.1 to 23.0) | 16.1 (13.9 to 18.6) | 14.9 (12.9 to 17.3) | 15.1 (13.0 to 17.5) | <0.001‡ |
| Age | 3992 | 60.8 (7.4) | 61.2 (7.4) | 61.1 (7.4) | 60.6 (7.2) | 60.5 (7.3) | 60.2 (7.5) | 0.001 |
| Grip strength (kPa) | 3992 | 0.73 (0.20) | 0.47 (0.11) | 0.65 (0.06) | 0.74 (0.06) | 0.83 (0.07) | 1.00 (0.12) | <0.001 |
| BMI (kg/m2) | 3984 | 26.1 (4.4) | 26.1 (4.8) | 25.7 (4.5) | 26.0 (4.3) | 26.3 (4.0) | 26.4 (4.4) | 0.011 |
| Height (cm) | 3986 | 161.6 (6.2) | 160.5 (6.3) | 161.1 (6.4) | 161.5 (6.3) | 161.9 (5.8) | 163.1 (5.8) | <0.001 |
| Systolic BP (mm Hg) | 3991 | 144.8 (23.6) | 142.8 (22.8) | 144.7 (23.9) | 145.5 (23.9) | 145.0 (24.2) | 146.3 (23.0) | 0.006 |
| Cholesterol (mmol/L) | 3998 | 7.0 (1.3) | 7.1 (1.3) | 7.0 (1.3) | 7.0 (1.2) | 6.9 (1.2) | 6.9 (1.3) | 0.007 |
| Triglycerides (mmol/L) | 3986 | 1.6 (1.0) | 1.6 (0.9) | 1.6 (0.9) | 1.6 (1.1) | 1.6 (1.0) | 1.6 (0.9) | 0.692 |
| Poor/not good health, % | 3986 | 50 | 69 | 49 | 45 | 45 | 39 | 0.178 |
| History of heart attack, % | 3979 | 3 | 4 | 2 | 2 | 4 | 2 | 0.005 |
| History of angina, % | 3983 | 7 | 10 | 6 | 5 | 6 | 5 | 0.001 |
| History of stroke, % | 3976 | 2 | 4 | 2 | 1 | 1 | 0.5 | <0.001 |
| History of asthma, % | 3975 | 9 | 11 | 10 | 7 | 7 | 7 | 0.008 |
| History of diabetes, % | 3976 | 3 | 3 | 4 | 2 | 2 | 3 | 0.294 |
| Blood pressure medication, % | 3975 | 17 | 19 | 17 | 16 | 17 | 17 | 0.609 |
| Smoke cigarettes, % | 3988 | 30 | 34 | 33 | 30 | 28 | 27 | 0.005 |
| No light physical activity, % | 3985 | 27 | 34 | 30 | 25 | 23 | 22 | <0.001 |
| No hard physical activity, % | 3948 | 86 | 91 | 86 | 84 | 84 | 82 | <0.001 |
| Low education, % | 3961 | 61 | 69 | 63 | 59 | 59 | 56 | <0.001 |
Figures are means (SD), unless stated otherwise. For brevity, descriptive statistics for only the ‘highest risk’ category of each categorical covariate are presented. Categorisations used are as follows: self-reported health status (poor, not so good, good, very good); history of heart attack (yes, no); history of angina (yes, no); history of stroke (yes, no); history of asthma (yes, no); history of diabetes (yes, no); use of blood pressure-lowering drugs (currently, previously but not now, never); current cigarette smokers (yes, no); light physical activity such as not sweating or out of breath during a typical week in the last year (none, less than one, one to two, three or more); hard physical activity such as sweating and/or out of breath during a typical week in the last year (none, less than one, one to two, three or more); education (primary (7–10 years), technical school/middle school, high school diploma (3–4 years), college/university <4 years, college/university 4 years or more).
*p Values for trend based on linear regression for the continuous variables, and logistic regression for the dichotomous ones. Grip in fifths treated as a continuous variable in the regression models.
†Mortality rate per 1000 (95% CI).
‡The trend across mortality rates calculated using Poisson regression adjusted for age and sex.
BMI, body mass index; BP, blood pressure.