eTable 2. Findings of subgroup analysis.
| Disorder type | Pooled prevalence (random-effects model) | Prevalence range | [95% confidence interval] | p | I2 [95% confidence interval] | No. of studies |
| All mental illness*1 | 77.5% | 65.1 to 93.8% | [72.4; 82.3] | 0.000 | 74.61 [53.98; 86.00] | 11 |
| Axis I disorders | 77.4% | 65.1 to 93.8% | [71.3; 82.9] | 0.000 | 75.93 [51.8; 87.98] | 8 |
| Subgroup analyses: | ||||||
| Data collected from 2000 onwards | 73.3% | 70.6 to 74.0% | [68.5; 77.9] | 0.898 | 0.00 [0.00; 3.24] | 3 |
| Data collected before 2000 | 80.6% | 56.7 to 93.8% | [71.1; 88.5] | 0.000 | 85.42 [67.78; 93.4] | 5 |
| Homeless women only | 83.3% | 70.6 to 93.8% | [56.9; 100.0] | 0.038 | 76.80 [0.00; 94.71] | 2 |
| Homeless men only | 76.6 % | 65.1 to 90.3% | [68.7; 83.7] | 0.000 | 80.87 [55.33; 91.81] | 5 |
| Participation rate >80% | 84.0% | 73.4 to 93.8% | [74.7; 91.6] | 0.001 | 81.90 [53.13; 93.01] | 4 |
| Participation rate <80% | 73.3% | 70.6 to 74.0% | [68.5; 77.9] | 0.000 | 0.00 [0.00; 3.24] | 3 |
| Sample size >100 | 73.6% | 65.1 to 80.8% | [68.0; 78.8] | 0.034 | 65.31 [0.00; 88.21] | 4 |
| Sample size <100 | 83.4% | 70.6 to 93.8% | [70.1; 93.5] | 0.004 | 77.71 [39.62; 91.77] | 4 |
| Interviewers: professional | / | / | / | / | / | 1 |
| Interviewers: non-professional | 81.5% | 73.4 to 93.8% | [71.4; 89.9] | 0.009 | 78.9 [32.48; 93.41] | 3 |
| Psychotic illnesses | 8.3% | 2.3 to 34.4% | [5.4; 11.8] | 0.002 | 65.50 [32.39; 82.40] | 10 |
| Subgroup analyses: | ||||||
| Data collected from 2000 onwards | 8.6% | 7.7 to 11.8% | [3.9; 14.7] | 0.486 | 0.00 [0.00; 0.00] | 2 |
| Data collected before 2000 | 8.2% | 2.3 to 34.4% | [4.9; 12.2] | 0.001 | 72.31 [43.22; 86.50] | 8 |
| Homeless women only | 23.1% | 11.8 to 34.4% | [5.0; 47.7] | 0.090 | 76.80 [0.00; 92.08] | 2 |
| Homeless men only | 7.6% | 4.9 to 9.6% | [5.8; 9.7] | 0.791 | 0.00 [0.00; 47.19] | 6 |
| Participation rate >80% | 9.8% | 4.9 to 34.4% | [4.9; 16.0] | 0.002 | 77.05 [44.38; 90.53] | 5 |
| Participation rate <80% | 6.6% | 2.3 to 11.8% | [3.5; 10.5] | 0.135 | 43.01 [0.00; 79.06] | 5 |
| Sample size >100 | 6.2% | 2.3 to 9.6% | [3.6; 9.5] | 0.076 | 56.32 [0.00; 85.52] | 4 |
| Sample size <100 | 10.8% | 4.9 to 34.4% | [5.4; 17.8] | 0.007 | 68.97 [26.91; 86.83] | 6 |
| Interviewers: professional | 7.4% | 4.9 to 9.6% | [4.3; 11.2] | 0.553 | 0.00 [0.00; 82.46] | 3 |
| Interviewers: non-professional | 12.9% | 6.6 to 34.4% | [4.2; 25.1] | 0.000 | 87.4 [64.18; 95.54] | 3 |
| Affective disorders | 15.2% | 5.6 to 46.9% | [9.8; 21.5] | 0.000 | 82.66 [67.18; 90.84] | 8 |
| Subgroup analyses: | ||||||
| Data collected from 2000 onwards | / | / | / | / | / | 1 |
| Data collected before 2000 | 15.8% | 5.6 to 46.9% | [9.6; 23.1] | 0.000 | 84.71 [70.30; 92.13] | 7 |
| Homeless women only | / | / | / | / | / | 1 |
| Homeless men only | 14.6% | 5.6 to 24.0% | [9.4; 20.6] | 0.004 | 73.88 [35.04; 89.5] | 5 |
| Participation rate >80% | 19.2% | 5.6 to 46.9% | [10.9; 29.0] | 0.000 | 85.32 [67.52; 93.36] | 5 |
| Participation rate <80% | / | / | / | / | / | 1 |
| Sample size >100 | 14.1% | 6.9 to 24.0% | [8.2; 21.2] | 0.001 | 81.63 [52.29; 92.93] | 4 |
| Sample size <100 | 16.5% | 5.6 to 46.9% | [5.4; 31.4] | 0.000 | 87.46 [70.1; 94.74] | 4 |
| Interviewers: professional | 13.4% | 11.0 to 15.9% | [8.7; 18.9] | 0.353 | 0.00 [0.00; 0.00] | 2 |
| Interviewers: non-professional | 25.9% | 16.3 to 46.9% | [14.0; 39.7] | 0.001 | 86.31 [60.44; 95.26] | 3 |
| Major depression | 11.6% | 0.00 to 40.6% | [4.4; 21.3] | 0.000 | 87.47 [73.15; 94.15] | 5 |
| Substance-related disorders | 60.9% | 47.1 to 74.0% | [53.1; 68.5] | 0.003 | 72.60 [36.88; 88.10] | 6 |
| Subgroup analyses: | ||||||
| Data collected from 2000 onwards | / | / | / | / | / | 1 |
| Data collected before 2000 | 62.1% | 51.9 to 74.0% | [53.9; 69.9] | 0.002 | 75.98 [41.24; 90.18] | 5 |
| Homeless women only | 58.3 % | 47.1 to 65.6 % | [40.4; 75.2] | 0.220 | 33.54 [0.00; 0.00] | 2 |
| Homeless men only | 68.5 % | 63.0 to 74.0 % | [57.2; 78.7] | 0.023 | 80.71 [17.52; 95.49] | 2 |
| Participation rate >80% | 67.7 % | 63.0 to 74.0 % | [59.3; 75.6] | 0.073 | 61.73 [0.00; 89.08] | 3 |
| Participation rate <80% | / | / | / | / | / | 1 |
| Sample size >100 | 61.6 % | 51.9 to 74.0 % | [52.3; 70.5] | 0.001 | 81.90 [53.01; 93.00] | 4 |
| Sample size <100 | 58.3 % | 47.1 to 65.6 % | [40.4; 75.2] | 0.220 | 33.54 [0.00; 0.00] | 2 |
| Interviewers: professional | / | / | / | / | / | 0 |
| Interviewers: non-professional | 67.7 % | 63.0 to 74.0 % | [59.3; 75.6] | 0.073 | 61.73 [0.00; 89.08] | 3 |
| Alcohol dependency | 55.4 % | 43.1 to 68.1 % | [49.2; 61.5] | 0.002 | 69.66 [36.82; 85.43] | 8 |
| Subgroup analyses: | ||||||
| Data collected from 2000 onwards | / | / | / | / | / | 1 |
| Data collected before 2000 | 55.6 % | 43.1 to 68.1 % | [48.5; 62.5] | 0.001 | 73.72 [43.74; 87.73] | 7 |
| Homeless women only | 52.0 % | 46.9 to 53.8 % | [43.2; 60.8] | 0.503 | 0.00 [0.00; 0.00] | 2 |
| Homeless men only | 61.2 % | 51.2 to 68.1 % | [54.2; 68.0] | 0.051 | 61.30 [0.00; 87.03] | 4 |
| Participation rate >80% | 59.6 % | 46.9 to 68.1 % | [52.7; 66.4] | 0.038 | 60.58 [0.00; 85.23] | 5 |
| Participation rate <80% | / | / | / | / | / | 1 |
| Sample size >100 | 55.1 % | 43.1 to 67.1 % | [45.6; 64.4] | 0.001 | 82.08 [53.71; 93.06] | 4 |
| Sample size <100 | 55.8 % | 46.9 to 68.1 % | [47.0; 64.4] | 0.097 | 52.52 [0.00; 84.31] | 4 |
| Interviewers: professional | / | / | / | / | / | 1 |
| Interviewers: non-professional | 59.7 % | 46.9 to 67.1 % | [50.8; 68.4] | 0.061 | 64.28 [0.00; 89.76] | 3 |
| Drug dependency | 13.9 % | 4.4 to 25.3 % | [7.2; 22.2] | 0.000 | 86.07 [71.78; 93.12] | 6 |
| Subgroup analyses: | ||||||
| Data collected from 2000 onwards | / | / | / | / | / | 1 |
| Data collected before 2000 | 11.7 % | 4.4 to 21.9 % | [6.0; 18.8] | 0.000 | 80.14 [53.26; 91.56] | 5 |
| Homeless women only | 24.6 % | 21.9 to 25.3 % | [17.4; 32.6] | 0.746 | 0.00 [0.00; 0.00] | 2 |
| Homeless men only | 10.1 % | 4.4 to 17.1 % | [4.8; 16.9] | 0.002 | 80.27 [47.92; 92.52] | 4 |
| Participation rate >80% | 11.7 % | 4.4 to 21.9 % | [6.0; 18.8] | 0.000 | 80.14 [53.26; 91.56] | 5 |
| Participation rate <80% | / | / | / | / | / | 1 |
| Sample size >100 | 6.5 % | 4.4 to 10.3 % | [1.9; 13.5] | 0.025 | 80.06 [14.29; 95.36] | 2 |
| Sample size <100 | 19.1 % | 12.5 to 25.3 % | [13.6; 25.3] | 0.203 | 34.85 [0.00; 77.23] | 4 |
| Interviewers: professional | / | / | / | / | / | 1 |
| Interviewers: non-professional | 9.6 % | 4.4 to 21.9 % | [3.0; 19.0] | 0.003 | 83.30 [49.35; 94.49] | 3 |
| Anxiety disorders | 17.6 % | 11.6 to 35.3 % | [12.9; 22.8] | 0.034 | 58.66 [0.00; 83.23] | 6 |
| Subgroup analyses: | ||||||
| Data collected from 2000 onwards | 23.7 % | 18.7 to 35.3 % | [9.7; 41.0] | 0.139 | 54.38 [0.00; 88.82] | 2 |
| Data collected before 2000 | 15.8 % | 11.6 to 28.1 % | [11.1; 21.1] | 0.072 | 57.06 [0.00; 85.75] | 4 |
| Homeless women only | 30.9 % | 28.1 to 35.3 % | [18.7; 44.6] | 0.598 | 0.00 [0.00; 0.00] | 2 |
| Homeless men only | 14.1 % | 11.6 to 18.7 % | [10.5; 18.1] | 0.232 | 31.46 [0.00; 92.87] | 3 |
| Participation rate >80% | 15.3 % | 11.6 to 28.1 % | [9.3; 22.3] | 0.062 | 64.08 [0.00; 89.71] | 3 |
| Participation rate <80% | 23.7 % | 18.7 to 35.3 % | [9.7; 41.0] | 0.139 | 54.38 [0.00; 88.82] | 2 |
| Sample size >100 | 14.1 % | 11.6 to 17.8 % | [10.7; 17.9] | 0.240 | 29.96 [0.00; 92.72] | 3 |
| Sample size <100 | 24.3 % | 18.7 to 35.3 % | [15.4; 34.3] | 0.235 | 30.98 [0.00; 92.82] | 3 |
| Interviewers: professional | / | / | / | / | / | 1 |
| Interviewers: non-professional | 15.3 % | 11.6 to 28.1 % | [9.3; 22.3] | 0.062 | 64.08 [0.00; 89.71] | 3 |
| Cognitive deficit*2 | 11.7 % | 0.00 to 35.2 % | [6.0; 18.9] | 0.000 | 86.65 [74.68; 92.96] | 7 |
| Subgroup analyses: | ||||||
| Data collected from 2000 onwards | / | / | / | / | / | 1 |
| Data collected before 2000 | 9.5 % | 0.00 to 15.3 % | [6.2; 13.3] | 0.033 | 58.89 [0.00; 83.32] | 6 |
| Homeless women only | / | / | / | / | / | 1 |
| Homeless men only | 15.5 % | 8.9 to 35.2 % | [8.2; 24.6] | 0.000 | 87.08 [72.15; 94.01] | 5 |
| Participation rate >80% | 9.8 % | 0.00 to 15.3 % | [5.8; 14.6] | 0.024 | 64.56 [6.90; 86.51] | 5 |
| Participation rate <80% | / | / | / | / | / | 1 |
| Sample size >100 | 9.2 % | 7.4 to 9.9 % | [6.9; 11.7] | 0.746 | 0.00 [0.00; 64.44] | 3 |
| Sample size <100 | 13.2 % | 0.00 to 35.2 % | [2.3; 29.7] | 0.000 | 90.37 [78.32; 95.72] | 4 |
| Interviewers: professional | 23.1 % | 14.6 to 35.2 % | [5.7; 46.4] | 0.002 | 89.83 [62.50; 97.24] | 2 |
| Interviewers: non-professional | 6.8 % | 0.00 to 9.99 % | [2.6; 12.6] | 0.040 | 68.98 [0.00; 90.97] | 3 |
| Personality disorders | 29.1 % | 14.7 to 55.1 % | [5.6; 59.5] | 0.000 | 96.84 [93.57; 98.45] | 3 |
*1Some studies reported point prevalences of mental illness, including personality disorders, with no further differentiation of Axis I disorders. Others reported only Axis I disorders and did not record information on personality disorders. Total mental illness summarizes all 11 studies and covers all reported mental illness, regardless of whether a distinction was made between Axis I and Axis II disorders. *2Based on the Mini-Mental Status Examination.