Table 1

Distribution of the covariates in the cohorts, in total and by suicide attempt status

TotalNo suicide attemptSuicide attemptP value
The 1950 cohort
N17 55517 371184
GPA, age 13 years. Mean (SD)3.18 (0.87)3.18 (0.87)3.06 (0.84)0.06
IQ test score, age 13 years. Mean (SD)64.7 (17.6)64.8 (17.5)61.8 (18.6)0.02
Educational level, age 38/43 years. N (%)0.06
 Primary and lower secondary, ≤9 years3986 (22.7)3939 (22.7)47 (25.5)
 Upper secondary, short track, 10–11 years5915 (33.7)5841 (33.6)74 (40.2)
 Upper secondary, long track, 12 years2218 (12.6)2196 (12.6)22 (12.0)
 Post secondary, >12 years5436 (31.0)5395 (31.1)41 (22.3)
Income*, age 38/43 years. Mean (SD)145.3 (92.2)145.4 (92.5)131.3 (58.0)<0.01
Parent’s low SES†, age 7/12 years. N (%)9477 (54.0)9361 (53.9)116 (63.0)0.01
Parents’ psychiatric diagnosis or suicidal behaviour, age 20/25–60/65 years‡. N (%)1991 (11.3)1954 (11.2)37 (20.1)<0.001
Women, N (%)8674 (49.4)8584 (49.4)90 (48.9)0.89
The 1970 cohort
N14 98714 815172
GPA, age 16 years. Mean (SD)3.27 (0.76)3.28 (0.76)2.68 (0.88)<0.001
IQ test score, age 13 years. Mean (SD)69.6 (17.4)69.7 (17.4)61.2 (17.2)<0.001
Educational level, age 26 years. N (%)<0.001
 Primary and lower secondary, ≤9 years1787 (11.9)1726 (11.7)61 (35.5)
 Upper secondary, short track, 10–11 years6479 (43.2)6398 (43.2)81 (47.1)
 Upper secondary, long track, 12 years4361 (29.1)4341 (29.3)20 (11.6)
 Post secondary, >12 years2358 (15.7)2348 (15.8)10 (5.8)
Parent’s low SES†, age 13 years. N (%)6194 (41.3)6126 (41.3)68 (39.5)0.63
Parents’ psychiatric diagnosis or suicidal behaviour, age 1/6-41/46 years‡. N (%)2959 (19.7)2908 (19.6)51 (29.7)<0.01
Women, N (%)7286 (48.6)7202 (48.6)84 (48.8)0.96
  • *Annual income in 1000 Swedish kronor/SEK.

  • †Manual occupation, farmers or no registered occupation.

  • ‡The participants’ age of measurement refers to parents’ psychiatric diagnoses and suicide attempts, while parents’ death by suicide was measured between participants’ age 0/4 years and 60/65 years in the 1950 cohort and 0 years and 41/46 years in the 1970 cohort. Details on age and years of measurements are presented in online supplemental table S1.

  • GPA, grade point average; SEK, Swedish krona; SES, socioeconomic status.