Kahl 2017.

Study characteristics
Methods	Retrospective, multicentre cohort study
Participants	793 women with FIGO stage IIIB to IV Median age, years (range) (% < 55 years): 60 (19 to 88) ECOG performance status (PS): 0 to 683 (86.1%); > 0 to 110 (13.9%) FIGO stages, n (%): IIIB ‐ 110 (13.9%) Stage IIIC ‐ 318 (40.1%) Stage IV ‐ 365 (46.0%) Ascites, mL: ≤ 500 to 450 (56.7%); > 500 to 343 (43.3%) Histology: high‐grade serous ‐ 660 (83.2%); others ‐ 133 (16.8%) Surgical complexity score: low/intermediate (≤ 7) ‐ 165 (20.8%); high (≤ 8) ‐ 628 (79.2%) Lymph node dissection: systematic ‐ 472 (59.5%); sampling ‐ 111 (14%); no ‐ 210 (26.5%) CDC: 0 to 2 ‐ 593 (74.8%); 3 to 4 ‐ 176 (22.1%); 5 ‐ 24 (3.0%) Germany
Residual disease details	Procedure performed by accredited gynaecological oncologist All women underwent primary cytoreductive surgery followed by postoperative systemic therapy with platinum‐based chemotherapy Residual disease was noted as follows, n (%): NMRD: 482 (60.8%) SVRD (1 mm to 10 mm): 226 (28.5%) LVRD (> 10 mm): 85 (10.7%) Women were divided into 3 groups based on their age‐adjusted Charlson Comorbidity Index (ACCI): low (0 to 1), intermediate (2 to 3), and high (≥ 4) Postoperative surgical complications were graded according to the Clavien‐Dindo classification (CDC)
Outcomes	Multivariate analysis of prognostic factors for OS: Residual disease (versus NMRD): SVRD (1 mm to 10 mm): HR 1.96 (95% CI 1.55 to 2.46) LVRD (> 10 mm): HR 2.75 (95% CI 2.01 to 3.77) Multivariate analysis of prognostic factors for high complications (CDC 3 to 5): Surgical complexity score: high (≤ 8): RR 1.70 (95% CI 1.01 to 2.85) Blood loss: ≥ 500: RR 1.0 (95% CI 0.64 to 1.44) Duration of surgery, minutes: ≥ 360: RR 1.84 (95% CI 1.24 to 2.72)
Risk of bias (QUIPS)	1. Study participation (a‐f): low risk Adequate number of participants and description of target population. Baseline characteristics, eligibility criteria, sampling frame and period/place study took place presented clearly. 2. Study attrition (a‐e): unclear risk Unclear if patients with incomplete follow‐up were excluded before arriving at the stated sample size. Insufficient information to permit judgement. 3. Prognostic factor measurement (a‐f): unclear risk Valid and reliable measurement of RD. Multicentre design may introduce heterogeneity in measurement of RD Outcome level assessment: Outcome: overall survival 4. Outcome measurement (a‐c): low risk Valid and reliable measurement of outcome 5. Adjustment for other prognostic factors (a‐g): unclear risk Ascites dichotomised along arbitrary cutoff of 500 mL. Multivariate model predicting OS adjusted for ACCI, ECOG, FIGO stage, histology and ascites. 6. Statistical analysis and reporting (a‐d): high risk No conceptual framework; criteria for variable selection into multivariate model is unclear. Dichotomisation of continuous variables also apparent. Outcome: progression‐free survival Not reported
Notes	After a median follow‐up was 47 months (interquartile range 18 to 87 months), 397 (50.1%) women had died. Significant differences between the 3 ACCI groups were detected for performance status (ECOG 0: 95.7% vs 84.2% vs 65.9%) and residual disease (NMRD 70.7% vs 55.3% vs 49.6%). Residual disease after debulking surgery was significantly more frequent in women with a high ACCI compared with women with an intermediate or low ACCI (50.4% vs 44.7% vs 29.3%) The mortality rate in the low‐ACCI group was 1.2%, in the intermediate‐ACCI group it was 2.3% and it was 9.8% for the high‐ACCI group