Table 2.
Quality assessment of the 10 studies included in the review. The Overall Quality Score was calculated by adding scores of items 1 to 6; CRD levels are: 1. Experimental studies, 2. Quasi-experimental studies, 3. Controlled observational studies, 3a. Cohort studies, 3b. Case control studies, 4. Observational studies without control groups, 5. Expert opinion based on theory, laboratory research or consensus; BD = Bipolar disorder, HC = healthy control
| Citation | Overall Quality Score (1–6) | CRD Hierarchy of evidence (Levels 1–5) | Sample size N < 30 small N = 30–50 medium N > 50 large |
Item 1 Representative sample |
Item 2 Matched control groups |
Item 3 Power analysis/Sample size calculation |
Item 4 Adequate assessment of inflammation |
Item 5 Adequate measure of cognition |
Item 6 Confidence intervals (CI) or or effect size (ES) |
|---|---|---|---|---|---|---|---|---|---|
| Criterion is fulfilled = 1 Criterion is not fulfilled = 0 |
|||||||||
| Dickerson et al. (2013) | 4 | 4 | Large, 107 BD | 1, patients were recruited in a psychiatric health care program, diagnosis was based on SCID | 0, No HC | 0 | 1 | 1 | 1, CI, no ES |
| Doganavsargil-Baysal et al. (2013) | 6 | 3 | Small/Medium 54 BDI 18 HC |
1, patients were recruited in an outpatient psychiatric clinic, diagnosis was based on DSM-IV TR | 1, HC matched by age, gender, educational level | 1 | 1 | 1 | 0, No CI, Estimated ES = 1 |
| Aas et al. (2013) | 3 | 3 | Large 249 BD 476 HC |
1: Patients recruited in hospitals, diagnosis based on DSM-IV criteria. | 0, HC not demographically matched | 0 | 1 | 1 | 0, No CI/ES |
| Barbosa et al. (2012) | 4 | 3 | Small, 25 BD 25 HC |
1, patients recruited in an out/inpatient psychiatric clinic, diagnosis based on Mini International Psychiatric inventory | 1, HC matched by age and gender | 0 | 1 | 1 | 0, No CI/ES |
| Chou et al. (2012) | 4 | 3 | Small 23 BD 33 HC |
1: patients were diagnosed based on DSM-IV criteria. | 1, age-matched HC | 0 | 1 | 1 | 0, No CI/ES |
| Dias et al. (2009) | 3 | 3 | Medium 65 BD 50 HC |
1, patients diagnosed based on DSM-IV criteria and Mini International Psychiatric inventory | 0, HC not demographically matched | 0 | 1 | 1 | 0, No CI/ES |
| Rybakowski et al. (2003) | 3 | 4 | Medium 54 BD I |
1: Outpatients recruited in hospitals, diagnosis based on DSM-IV criteria. | 0, No HC | 0 | 1 | 1 | 0, No CI/ES |
| Rybakowski et al. (2006) | 3 | 3 | Large 111 BD 160 HC |
1: inpatients recruited in hospitals, diagnosis based on DSM-IV criteria. | 0, Not matched | 0 | 1 | 1 | 0, No CI/ES |
| Rybakowski et al. (2010) | 4 | 3 | Large 60 BD 60 HC |
1: Patients attending an outpatient lithium clinic, diagnosis based on DSM-IV criteria - SCID | 1, age and gender-matched HC | 0 | 1 | 1 | 0, No CI/ES |
| Tramontina et al. (2009) | 4 | 4 | Medium 64 BD I |
1: outpatients recruited in a hospital setting, diagnosis based on DSM-IV criteria. | 0, No HC | 1 | 1 | 1 | 0, No CI/ES |