Table 1 Observational studies examining the relationship between fish intake and serum omega-3 fatty acid levels on outcomes in haemodialysis patients

Kutner 2002 [10]. USA

216 incident HD patients (53 % male, aged 20–90 year)

Mean, 3 years

Regular fish eaters versus non-fish eaters

All-cause mortality

RR 0.50 (95 % CI 0.27–0.90)

Friedman 2008 [12]. USA

93 HD patients (66 % male, aged ≥18 years)

Median, 755 days (range 40–770 days)

Omega-3 index < 4.69 % versus omega-3 index > 4.69 %

All-cause mortality

HR 2.48 (95 % CI 0.88–6.95)

Noori 2011 [11]. USA

145 HD patients (57 % male, 53 ± 14 years)

6 years

Quartiles of dietary omega-6 to omega-3 ratio (1) 1.7–7.6, (2) 7.6–9.3, (3) 9.3–11.3, (4) 11.3–17.4]

All-cause mortality

Highest (4): Reference (1.00); (3): HR 0.67 (95 % CI 0.25–1.79); (2): HR 0.30 (95 % CI 0.09–0.99); (1): HR 0.39 (95 % CI 0.14–1.18)

Hamazaki 2011 [13]. Japan

176 HD patients (55 % male, 64 ± 12 years)

5 years

Erythrocyte DHA levels > 8.1 % versus DHA levels < 7.2 %

All-cause mortality

HR 0.43 (95 % CI 0.21–0.88)

Terashima 2014 [14]. Japan

As176 HD patients (55 % male, 64 ± 12 years)

10 years

Erythrocyte DHA levels > 8.1 % versus DHA levels < 7.2 %

All-cause mortality

HR 0.52 (95 % CI 0.30–.0.91)

Friedman 2013 [16]. USA

N = 100 (died in 1^st year of HD, 58 % male, 67 ± 14 years) N = 300 (survived 1st year of HD, 58 % male, 66 ± 14 years)

Retrospective analysis

Quartiles of serum omega-3 fatty acid levels [(1) 1.3 %–3.1 %, (2) 3.1 %–3.8 %, (3) 3.8 %–4.5 %, (4) 4.5 %–15.1 %]

Sudden cardiac death

Lowest (1): Reference (1.00); (2): OR 0.37 (95 % CI 0.17–0.79); (3): OR 0.22 (95 % CI 0.09–0.51); (4): OR 0.20 (95 % CI 0.08–0.51)

Shoji 2013 [15]. Japan

517 HD patients (63 % male, aged 61 [IQR 54–68] yrs)

5 years

Quartiles of serum omega-3 to omega-6 ratio [medians: (1) 0.73, (2) 1.02, (3), 1.27, (4) 1.68]

Cardiovascular events

Highest (4): Reference (1.00); (3): HR 1.35 (95 % CI 0.86–2.04); (2): HR 1.31 (95 % CI 0.85–2.02); (1): HR 1.93 (95 % CI 1.27–2.95)