Table 3.

Review of bias for 16 included studies based on the Newcastle Ottawa Scale

Criteria	*Hershman 200919	*Griggs 201416	*Griggs 200317	*Griggs 200721	*Simon 201222	*Hershman 200521	*Reyes 201633	Gwyn 200426	Gorin 200627	*Fedewa 201033	Vander grift 201328	*Hershman 200629	McLaughlin 2012	*Chavez-MacGregor 2016	*Nurgalieva 2013	*Gagliato 2014
Representativeness of the exposed cohort	0 – clinical trial participants in SWOG	1 – low income, multi-ethnic women in Breast and Cervical Cancer Prevention Treatment Program	1- treatment sites from Monroe County (New York) and Henry Ford Health System (Michigan) tumor registries	1- Multicentr observational study of cancer patients starting chemotherapy for nonmyeloid malignancies	1- Treatment sites from Henry Ford Health System	1- Treatment sites from Henry Ford Health System	0 – Multicenter clinical trial participants among 8 inner city hospitals evaluating patient assistance plan usage	0 – derived from prior case-control study of breast cancer patients residing in Atlanta, GA	1 – SEER Medicare	1 – Patients from the National Cancer Data Base, hospital based cancer registry	1 – NCCN outcome database	1 – SEER-Medicare	0 – North Carolina Cancer Registry and Medicaid linked database	1 – California Cancer Registry (CCR)	1 – SEER Medicare	0 – Single center study of MD Anderson Cancer Center patients
Selection of the non-exposed Cohort	1- uses same source	1- uses same source	1- uses same source	1- uses same source	1- uses same source	1- uses same source	1- uses same source	1- uses same source	1- uses same source	1- uses same source	1- uses same source	1- uses same source	1- uses same source	1- uses same source	1- uses same source	1- uses same source
Ascertainment of Exposure	1 – self-reported race according to NCI reporting criteria at time of enrollment	1 – self-reported race obtained through telephone interview	0 – obtained from medical record, not stated if self-reported	0 – obtained from medical record or patient interview, unknown if self-reported	0 – obtained from medical record, unknown if self-reported	0 – obtained from administrative databases, unknown if self-reported	1- self reported race	1 – self-reported race	0 – obtained from SEER data	0 – obtained from database, unknown if self reported	0 – obtained from database, unknown if self reported	0 – obtained from SEER data	0 – obtained from database, unknown if self-reported	0 – obtained from CCR, unknown if self-reported	0 – obtained from SEER data	0 – obtained from medical record, unknown if self-reported
Adjustment for confounding	1- HR status Tumor size Axillary nodal status Menopausa1 status Baseline ANC BSA Did not include comorbidities, socioeconomic factors	1-Age CC1 Years of education Social Support Patient self efficacy BMI Academic v non-academic treatment site Hormone receptor status Did not include baseline ANC	2- Age Insurance Type Census block group Per Capita Income CCI BMI Chemotherapy regimen Treatment site Reasons for changes in chemotherapy Menopausal status Tumor size LN involvement HR status Initial WBC count	0 - Age CCI Marital status Occupation Employment status BMI HR status Did not include tumor size, nodal status, baseline ANC	0 – Age Insurance status CCI Deprivation index Did not include disease characteristics	0- Age Stage CCI Hormone receptor status Chemotherapy with or without doxorubicin Did not include LN status, tumor size, socioeconomic factors	1- Age CCI Level of education Insurance status Employment status Marital status Hormone receptor status Tumor size Mastectomy Mental/Physical Health Status Perceptions/treatment beliefs Side effects	2 - Age Insurance status Poverty Index Marital Status BMI Education level Insurance type Mammography history Method of detection Number of comorbidities Smoking status Breast self-exam Bra cup size LN status Tumor size Disease stage	2 - Age Marital status Population of city of residency Stage Hormone receptor status Tumor size Lymph node involvement Comorbid conditions Method of cancer detection Member of HMO Year of diagnosis Physician visits per year Census tract percentage in poverty	2 - Age CCI Population without high school diploma Treatment facility type Volume of patients with breast cancer at facility Census region Insurance Stage Hormone receptor status Year diagnosis	2 – Age CCI BMI Stage Lymph node status Hormone receptor status HER2 status Grade LVI Pathologic upstage Number of excisional procedures Reconstruction before adjuvant therapy Received ALND Diagnostic breast US Diagnostic breast MRI 21 gene RT PCR assay Type of Diagnostic biopsy Treating institution Type of initial surgery	2 - Age Live in metropolitan area Stage Hormone receptor status Tumor Grade Comorbid conditions SES score Marital status Teaching hospital Surgery performed Radiation Received	2- Age Race Marital status Year at diagnosis County-level metropolitan and HPSA status Stage Tumor size Hormone receptor status CCI Disability status Assisted living and home health Surgery Type Treatment Type	2 - Age Sex Year of diagnosis SES, breast cancer stage, Breast cancer subtype, Marital status Type of breast surgery, whether reconstructive surgery was performed, Primary payer, Treatment at an NCI-designated cancer center	1- Age Marriage status Tumor stage, size, grade Hormone receptor status Comorbidity Year of diagnosis SEER region Primary surgery and radiotherapy, and chemotherapy No information on socioeconomic status or comorbidities	1- Age Race/ethnicity Pathologic tumor size according to TNM classification (T1, T2, T3–4) Pathologic nodal status according to TNM classification (N1, N2, N3) Histologic grade LVI Type of surgery Number of comorbidities (0, 1 to 2, 3 to 4, or 5+) No information on socioeconomic status or comorbidities
Assessment of Outcome	1 – objective measure	1 – objective measure	1 – objective measure	1 – objective measure,	1 – objective measure	1 – objective measure	1 – objective measure	1 – objective measure	1 – objective measure	1 – objective measure	1 – objective measure	1 – objective measure	1 – objective measure	1 – objective measure	1 – objective measure	0 – date of administration of chemotherapy defined as date of first chemotherapy claim
Was follow-up long enough for outcomes to occur	1 - yes	1 - yes	1 - yes	1 - yes	1 - yes	1 - yes	1 - yes	1 - yes	1 - yes	1 - yes	1 - yes	1 - yes	1 - yes	1 - yes	1 - yes	1 - yes
Adequacy of follow-up of cohorts	1- Adequate	1 – Adequate	1 – Adequate 3% with missing covariate data	1- Adequate 7% did not have information on actual chemotherapy dose received, 4% were missing covariate information	1- Adequate	1- Adequate	1 – Adequate 2% with missing data on chemotherapy cycles planned or completed	1 – Adequate Response rate of 88% in original case-control study, possible source of bias	1 – Adequate Missing billing data for delay outcomes, possible source of bias	1 – Adequate Reason for chemotherapy nonadministration unknown for 5.6%	1 – Adequate	1 – Adequate	1 – Adequate 8% excluded due to incomplete treatment information, treatment delay > months or refusal of treatment	1 – Adequate 20% excluded due to incomplete treatment information available	1 – Adequate	1 – Adequate

^*Included in meta-analysis