Background Previous studies have shown inconsistent findings on the association between psychological distress and risk of mortality. This study aimed to address this inconsistent association using a large US population-based cohort.

Methods This study used data from 1997 to 2009 US National Health Interview Survey, which were linked with National Death Index through 31 December 2011. Psychological distress was measured using Kessler-6 scale and was categorised into six groups based on scores as 0, 1–3, 4–6, 7–9, 10–12 and ≥13. Main outcomes were all-cause, cancer-specific and cardiovascular disease (CVD)-specific mortality. Analyses were completed in 2019. Cox proportional hazards models were used to determine the association between psychological distress and mortality.

Results A total of 330 367 participants aged ≥18 years were included. During a mean follow-up of 8.2 years, 34 074 deaths occurred, including 8320 cancer-related and 8762 CVD-related deaths. There was a dose–response association between psychological distress and all-cause mortality. Compared with the 0 score category, adjusted HRs (95% CIs) for other categorical psychological distress scores, that is, 1–3, 4–6, 7–9, 10–12 and ≥13, were 1.09 (1.05 to 1.12), 1.22 (1.17 to 1.27), 1.38 (1.31 to 1.46), 1.49 (1.40 to 1.59) and 1.57 (1.47 to 1.68), respectively. Corresponding values for cancer-specific mortality were 1.06 (0.99 to 1.12), 1.13 (1.04 to 1.23), 1.27 (1.14 to 1.42), 1.38 (1.22 to 1.57) and 1.32 (1.15 to 1.51), respectively; those for CVD-specific mortality were 1.11 (1.05 to 1.18), 1.22 (1.12 to 1.32), 1.30 (1.17 to 1.45), 1.38 (1.20 to 1.58), and 1.46 (1.27 to 1.68), respectively.

Conclusions We found a dose–response relationship between psychological distress and all-cause and cause-specific mortality, emphasising the need for early prevention strategies among individuals with potential psychological distress.