Table 3.
Number of serum biomarkers, quartiles of multi-biomarker scores, and probabilities of suicidal behaviour during 12-month follow-up (N = 884)
| Increased suicidal severitya | Fatal/non-fatal suicide attempt | |||||||
|---|---|---|---|---|---|---|---|---|
| N | Present, N (%) | OR (95% CI) | p value for trend | N | Present, N (%) | OR (95% CI) | p value for trend | |
| Number of serum biomarkersb | ||||||||
| 0 | 60 | 2 (3.3) | Reference | <0.001 | 268 | 1 (0.4) | Reference | <0.001 |
| 1 | 214 | 14 (6.5) | 2.10 (0.46–9.55) | 381 | 5 (1.3) | 3.30 (0.38–28.89) | ||
| 2 | 252 | 39 (15.5) | 5.17 (1.20–22.26) | 194 | 22 (11.3) | 29.24 (3.76–227.47) | ||
| 3 | 236 | 59 (25.0) | 9.08 (2.12–38.85) | 41 | 10 (24.4) | 63.29 (7.21–555.44) | ||
| 4 | 102 | 33 (32.4) | 12.02 (2.69–53.69) | |||||
| 5 | 20 | 8 (40.0) | 16.06 (2.87–90.03) | |||||
| Quartiles of multi-biomarker scoresc | ||||||||
| 1 (lowest) | 213 | 12 (5.6) | Reference | <0.001 | 268 | 1 (0.4) | Reference | <0.001 |
| 2 | 219 | 27 (12.3) | 2.20 (1.07–4.51) | 137 | 0 (0.0) | 0.99 (0.00–0.00) | ||
| 3 | 245 | 53 (21.6) | 4.29 (2.19–8.41) | 244 | 5 (2.0) | 5.36 (0.61–46.82) | ||
| 4 | 207 | 63 (30.4) | 6.20 (3.15–12.19) | 235 | 32 (13.6) | 32.34 (4.20–248.99) | ||
Increase in Brief Psychiatric Rating Scale suicidality item score during the follow-up compared to the baseline.
Odds ratios (95% confidence intervals) [OR (95% CI)] were estimated by using logistic regression analyses after adjustment for age, gender, living alone, religious affiliation, monthly income, atypical feature, number of depressive episodes, number of physical disorders, smoking status, scores on Hospital Anxiety & Depression Scale-anxiety subscale and Alcohol Use Disorders Identification Test, and treatment step.
For calculating the number of serum biomarkers, 0 (favourable) or 1 (unfavourable) score from the optimal cut-offs of each significant biomarker was generated, and then summed scores were estimated ranging from 0 to 5, with higher scores indicating more unfavourable condition.
For calculating the continuous multi-biomarker scores, the following equations were used: Increased suicidal severity = (0.331 × cortisol) + (1.108 × interleukin-1β) + (0.700 × total cholesterol) + (0.193 × folate) + (0.282 × homocysteine); and fatal/non-fatal suicide attempt = (1.843 × cortisol) + (1.215 × total cholesterol) + (1.010 × folate), respectively. Then, quartiles of the multi-biomarker scores were generated ranging from 1 to 4, with higher scores indicating higher risk.