Demographic group differences
Sample characteristics of each occupation are presented in Table 1. Occupations differed regarding the proportion of women, χ2(2) = 129.88, p < .001. Police officers and firefighters included predominately male participants whereas the medical staff group comprised more women. Occupational groups also differed in mean age, F(2, 574) = 6.37, p = .002, η2 = .02. After applying Bonferroni-Holm’s correction, post-hoc tests revealed that police officers were significantly older than medical staff, t(457) = -2.84, padjusted = .010, d = 0.27, and firefighters, t(345) = 3.06, padjusted = .006, d = 0.33. There was no difference between medical staff and firefighters, t(319) = 0.79, p = .431, d = 0.09. Moreover, occupations differed significantly regarding their years of work experience, F(2, 574) = 25.42, p < .001, η2 = .09. Post-hoc tests revealed that medical staff reported significantly fewer years of work experience than police officers and firefighters, t(543) = -6.06, padjusted < .001, d = 0.52. However, there was no difference between police officers and firefighters, t(543) = 1.93, p = .054, d = 0.17. Shift work was more common in medical staff and police officers than in firefighters, χ2(2) = 60.11, p < .001. Of those working shifts, especially police officers reported an increased number of night shifts, χ2(2) = 23.26, p < .001. Standby shifts were most frequent in medical staff compared to lower rates in police officers and firefighters, χ2(2) = 38.94, p < .001.
Table 1
Sample characteristics per occupational group
| Medical staff | Police officers | Firefighters | | p |
Sex (% women) | 68.61 | 28.40 | 9.00 | χ2(2) = 129.88 | < .001 |
Age (in years) | 37.05 (11.64) | 40.05 (11.35) | 35.96 (11.26) | F(2, 574) = 6.37 | .002 |
Job experience (in years) | 12.34 (9.69) | 19.82 (11.98) | 17.29 (11.16) | F(2, 574) = 25.42 | < .001 |
Shift work (%) | 74.00 | 64.20 | 26.00 | χ2(2) = 60.11 | < .001 |
Night shifts (% of those working shifts) | 76.43 | 93.93 | 69.20 | χ2(2) = 23.26 | < .001 |
Standby duty (%) | 49.68 | 16.70 | 34.62 | χ2(2) = 38.94 | < .001 |
Group Differences: Psychopathological Symptoms
General psychopathological symptoms. An ANOVA with occupation as between-subject factor and GSI scores as dependent variable showed no significant group differences regarding psychopathological symptom burden, F(2, 568) = 0.79, p = .455, η2 = .00.
Posttraumatic-stress symptoms. An ANOVA with occupation as between-subject factor and IES-R total scores as dependent variable revealed no significant group differences, F(2, 495) = 2.31, p = .101, η2 = .01.
Burnout symptoms. A MANOVA with occupation as between-subject factor and MBI-subscale scores as dependent variables revealed significant group differences, F(6, 1134) = 9.89, p < .001, η2 = .05. Univariate comparisons, yielded significant differences for each subscale; emotional exhaustion: F(2, 568) = 15.27, padjusted < .001 η2 = .05; depersonalization: F(2, 568) = 13.97, padjusted < .001, η2 = .05; personal accomplishment: F(2, 568) = 4.98, p = .007, η2 = .02. Post-hoc tests revealed that police officers reported higher levels of emotional exhaustion than medical staff, t(573) = 5.06, padjusted < .001, d = 0.42, and that emotional exhaustion was higher in medical staff than in firefighters, t(573) = -3.50, padjusted < .001, d = -0.29. Moreover, police officers showed significantly higher rates of depersonalization compared to both other groups, t(574) = 5.10, padjusted < .001, d = 0.43, while medical staff and firefighters did not differ, t(574) = − .14, p = .887, d = -0.01. Concerning personal accomplishment, medical staff showed higher rates than both other groups, t(569) = 3.14, padjusted = .004, d = 0.26, while police officers and firefighters reported comparable levels, t(569) = 0.30, p = .765, d = 0.03.
Table 2
Means, standard deviations and group differences of health outcomes and health-benefitting factors
| Medical staff (MS) | Police officers (PO) | Fire-fighters (FF) | | p | Significant post-hoc tests |
Health outcomes | | | | | | |
General mental health problems | 15.37 (5.41) | 15.91 (5.29) | 15.24 (6.38) | F(2, 568) = 0.79 | .455 | |
Posttraumatic stress symptoms | 29.67 (22.49) | 30.31 (23.36) | 24.58 (19.29) | F(2, 495) = 2.31 | .101 | |
Burnout | | | | | | |
Emotional exhaustion | 16.54 (10.35) | 18.99 (11.17) | 12.01 (10.10) | F(2, 573) = 15.26, | < .001 | PO > MS > FF |
Depersonalization | 6.68 (5.95) | 9.36 (6.44) | 6.57 (5.88) | F(2, 574) = 13.80 | < .001 | PO > (MS = FF) |
Personal accomplishment | 30.21 (7.69) | 28.06 (8.51) | 27.77 (7.93) | F(2, 569) = 5.15 | .006 | MS > (PO = FF) |
Health-benefitting factors | | | | | | |
Sense of coherence | 46.58 (7.59) | 45.11 (7.52) | 46.84 (7.84) | F(2, 577) = 3.02 | .050 | PO < (MS = FF) |
Trait resilience | 60.94 (10.14) | 60.98 (10.18) | 60.02 (9.69) | F(2, 575) = 0.36 | .700 | |
Internal LOC | 4.14 (0.62) | 3.94 (0.72) | 4.18 (0.61) | F(2, 577) = 7.05 | .001 | PO < (MS = FF) |
External LOC | 2.40 (0.77) | 2.61 (0.82) | 2.34 (0.82) | F(2, 577) = 5.61 | .004 | PO > (MS = FF) |
Note. Significant group differences are bold. |
FF = firefighters; LOC = Locus of control; MS = Medical staff; PO = police officers |
Group Differences: Health-benefitting Factors
General psychopathological symptoms. Comparing two models predicting general mental health problems based on SOC, trait resilience, internal, and external LOC allowing the regression coefficients to vary across groups or not, had no impact on the model fit, ∆χ2(8) = 12.91, p = .115, indicating no differences between the occupations regarding the prediction of general mental health problems.
Posttraumatic-stress symptoms. Applying the same model comparison to posttraumatic stress, the test revealed a significant difference between models, ∆χ2(8) = 22.15, p < .001. Model comparisons between models fixing regression coefficients across all groups and models allowing one path to vary across groups, revealed significant fit differences for external LOC, ∆ χ2(2) = 9.25, p = .001 (see Table 4 for all paths). Regarding regression coefficients, SOC descriptively remained the strongest predictor of posttraumatic stress for all occupations (see Table 5). However, external control beliefs explained a larger amount of variance in posttraumatic stress symptoms in police officers compared to firefighters, diff = .31, padjusted < .001, and medical staff, diff = .21, padjusted < .001, but there was no difference between medical staff and firefighters, diff = .10, p = .111, where external control beliefs were no longer a significant predictor of posttraumatic stress symptoms.
Burnout symptoms. Concerning burnout symptoms, the model comparison indicated significant differences across the different occupations regarding emotional exhaustion, ∆χ2(8) = 17.40, p = .026, and personal accomplishment, ∆χ2(8) = 28.92, p < .001, but no differences for depersonalization, ∆χ2(8) = 7.31, p = .504. Concerning emotional exhaustion, model comparisons did not reveal significant fit differences for models allowing one path to vary across groups (see Table 4). Regarding personal accomplishment, model comparisons presented in Table 3 showed significant fit differences between a model fixing all regression coefficients and a model allowing one path to differ across groups for each predictor variable. However, comparing the regression coefficients between the occupations, there was only one significant difference reflected in a larger association of SOC and personal accomplishment in medical staff than in firefighters, diff = .05, padjusted = .021.
Table 4
Fit differences between models fixing all regression coefficients across groups and models allowing one path to vary across groups
Outcome | Model comparisons |
Posttraumatic stress | |
Sense of coherence | ∆ χ2(2) = 5.67, p = .059 |
Trait resilience | ∆ χ2(2) = 4.55, p = .103 |
Internal LOC | ∆ χ2(2) = 2.18, p = .337 |
External LOC | ∆ χ2(2) = 9.25, p = .001 |
Burnout | |
Emotional exhaustion | |
Sense of coherence | ∆ χ2(2) = 1.20, p = .548 |
Trait resilience | ∆ χ2(2) = 4.41, p = .111 |
Internal LOC | ∆ χ2(2) = 2.84, p = .242 |
External LOC | ∆ χ2(2) = 0.95, p = .620 |
Personal accomplishment | |
Sense of coherence | ∆ χ2(2) = 6.34, p = .042 |
Trait resilience | ∆ χ2(2) = 17.72, p < .001 |
Internal LOC | ∆ χ2(2) = 10.53, p = .005 |
External LOC | ∆ χ2(2) = 10.05, p = .007 |
Note. Significant group differences are bold. LOC = Locus of control |
Table 5
Differences of path analyses between occupations
| Medical staff | Police officers | Fire-fighters | |diff 1| | padjusted | |diff 2| | padjusted | |diff 3| | p |
General mental health | | | | | | | | | |
Sense of coherence | − .68 | − .49 | − .68 | | | | | | |
Trait resilience | − .12 | − .25 | − .26 | | | | | | |
Internal LOC | .08 | .04 | .02 | | | | | | |
External LOC | .02 | .05 | .05 | | | | | | |
Posttraumatic stress | | | | | | | | | |
Sense of coherence | − .24 | − .36 | − .44 | .20 | .174 | | | | |
Trait resilience | .01 | − .15 | .06 | .21 | | | | | |
Internal LOC | − .14 | .06 | − .25 | .31 | | | | | |
External LOC | .07 | .28 | − .03 | .31 | < .001 | .21 | < .001 | .10 | .111 |
Burnout | | | | | | | | | |
Emotional exhaustion | | | | | | | | | |
Sense of coherence | − .57 | − .28 | − .36 | .29 | | | | | |
Trait resilience | − .02 | − .25 | − .04 | .23 | | | | | |
Internal LOC | − .04 | − .10 | − .27 | .23 | | | | | |
External LOC | .02 | .15 | .11 | .09 | | | | | |
Depersonalization | | | | | | | | | |
Sense of coherence | − .43 | − .43 | − .39 | | | | | | |
Trait resilience | − .04 | − .03 | .13 | | | | | | |
Internal LOC | .09 | − .06 | − .10 | | | | | | |
External LOC | − .06 | − .04 | .10 | | | | | | |
Personal accomplishment | | | | | | | | | |
Sense of coherence | − .44 | − .43 | − .39 | .05 | .021 | .04 | .082 | | |
Trait resilience | − .04 | − .03 | .13 | .17 | .100 | | | | |
Internal LOC | .09 | − .06 | − .10 | .19 | .099 | | | | |
External LOC | − .06 | − .04 | .09 | .15 | .840 | | | | |
Note. Unstandardized coefficients are reported as estimated in the grouped path analysis. Significant regression coefficients in each group model are bolded (p < .05). Differences between medical staff, police officers and firefighters are italicized for emphasis. p-values are adjusted using Bonferroni-Holm’s correction. Regression coefficients are grey if the model comparison in Table 4 did not indicate significant group differences. |
diff 1 = Largest difference between regression coefficients that could be calculated. diff 2 = Second largest difference. diff 3 = Remaining comparison. LOC = Locus of control.
Bivariate Correlations
Table 2 shows the bivariate correlations between health-benefitting factors and different measures of psychopathological symptom burden. All health-benefitting factors were significantly correlated with mental health outcomes (all ps < .001). The strongest association was found between SOC and general psychopathological symptom burden, r = − .73, p < .001, indicating that a stronger SOC was related to lower symptom levels. As hypothesized, higher levels of SOC, resilience, and a stronger internal LOC were related to less severe general mental health problems, lower levels of posttraumatic stress, and fewer burnout symptoms. Conversely, stronger external control beliefs were linked to more severe general mental health problems, higher levels of posttraumatic stress, and more burnout symptoms.
Table 3
Bivariate Pearson correlations of health-benefitting factors and psychopathological symptoms
| 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 |
SOC (1) | .84 | .54** | .50** | − .53** | − .73** | − .49** | − .59** | − .44** | .42** |
Resilience (2) | | .90 | .45** | − .31** | − .52** | − .34** | − .40** | − .23** | .48** |
LOCinternal (3) | | | .36 | − .44** | − .38** | − .35** | − .42** | − .24** | .33** |
LOCexternal (4) | | | | .37 | .43** | .38** | .41** | .24** | − .18** |
GSI (5) | | | | | .96 | .53** | .59** | .37** | − .32** |
IES-Rtotal (6) | | | | | | .93 | .45** | .27** | − .30** |
MBIEE (7) | | | | | | | .90 | .58** | − .25** |
MBIDP (8) | | | | | | | | .75 | − .20** |
MBIPA (9) | | | | | | | | | .75 |
Note. The diagonal shows the reliabilities (Cronbach’s α). |
** p < .001 |
SOC = Sense of coherence; LOC = Locus of control; GSI = Global Severity Index as measured by the Brief Symptom Inventory; IES-R = Impact of Event Scale-Revised; MBI = Maslach Burnout Inventory; MBIEE = MBI Emotional exhaustion; MBIDP = MBI Depersonalization; MBIPA = MBI Personal accomplishment |
Regression Models
General psychopathological symptoms. A multiple regression showed that 56% of general mental health problems were explained by SOC, trait resilience, and internal and external control beliefs, F(4, 566) = 179.30, p < .001. All predictors except for internal control beliefs, β = .05, t(566) = 1.33, ∆R2 = .00, accounted for a unique amount of variance in symptom severity [SOC, β = − .61, t(566) = -16.10, ∆ R2 = .20, p < .001, trait resilience, β = − .19, t(565) = -5.57, ∆R2 = .02, p < .001, external control beliefs, β = .07, t(565) = 2.16, ∆ R2 = .00, p = .031].
Posttraumatic-stress symptoms. Regarding posttraumatic stress, 27% of variance in symptom severity could be collectively explained by the set of health-benefitting factors, F(4, 493) = 45.18, p < .001. However, only SOC, β = − .33, t(493) = -6.13, ∆R2 = .06, p < .001, and an external LOC, β = .15, t(493) = 3.20, p = .001, ∆R2 = .02, accounted for unique amounts of variance.
Burnout symptoms. Together, SOC, trait resilience, and LOC explained 38% of the variance of symptoms of emotional exhaustion, F(4, 571) = 88.19, p < .001. On a single predictor level, all variables were significant predictors of emotional exhaustion, with SOC being the strongest, β = − .43, t(571) = -9.63, ∆R2 = .10, p < .001, followed by internal LOC, β = − .12, t(571) = -2.98, ∆R2 = .01, p = .003, external LOC, β = .10, t(571) = 2.58, ∆R2 = .01, p = .005, and trait resilience, β = − .09, t(571) = -2.16, ∆R2 = .01, p = .003. Regarding depersonalization, only 19% of the variance were explained by all predictors, F(4, 572) = 33.70, p < .001, whilst only SOC accounted for an unique amount of variance, β = − .42, t(572) = -8.31, ∆R2 = .10, p < .001. Concerning personal accomplishment, the set of predictors accounted for 28% of the variance, F(4, 567) = 53.79, p < .001. Trait resilience was the strongest predictor, β = .43, t(567) = 7.84, ∆R2 = .08, p < .001, followed by SOC, β = .23, t(567) = 4.70, ∆R2 = .03, p < .001, an internal LOC, β = .10, t(567) = 2.27, ∆R2 = .01, p = .024, and an external LOC, β = .09, t(567) = 2.02, ∆R2 = .01, p = .045. See Appendix A for a table presenting all regression results.