COVID-19 and self-reported health of the Norwegian adult general population: A longitudinal study 3 months before and 9 months into the pandemic.

The COVID-19 pandemic had a global impact on daily lives, and this study aimed to assess the effects on broader aspects of health in the general population of Norway. This population-based cohort study assessed changes in health of the Norwegian general population from 3 months before to 9 months during the COVID-19 pandemic. Sampling was based on the results of Norwegian surveys designed for collecting general population norms for health measurement instruments. In December 2019, 12,790 randomly selected adults aged ≥18 years received a postal questionnaire. The 3,200 respondents received a similar follow-up postal questionnaire including the EQ-5D-5L, PROMIS-29 instruments, and questions about respondents having or having had COVID-19. Score changes were compared to estimates for the minimal important change (MIC) and age-related change. Association of instrument change scores with baseline characteristics, health problems, and having had COVID-19 was determined using multivariable linear regression. Of 3101 respondents with unchanged addresses, 2423 (78.1%) responded to the second survey. For all respondents, EQ VAS and PROMIS-29 scores for 6 of 8 domains were slightly poorer (p<0.01) than before COVID-19, and the mean change was below the MIC. In multivariable analyses, the greatest number of poorer outcomes were associated with being female, 18-29 years, or ≥80 years of age (p<0.01); > MIC for ≥ 80 years of age and EQ-5D index, PROMIS-29 physical function and social participation. Respondents who had COVID-19 had poorer outcomes for PROMIS-29 social participation (> MIC). Those reporting COVID-19 in their partner/family and not themselves, had poorer outcomes for PROMIS-29 anxiety and social participation. About 9 months into the COVID-19 pandemic, EQ-5D-5L and PROMIS-29 domain scores showed slightly poorer health in the Norwegian adult general population compared to 1 year earlier in the same respondents. The overall changes were less than expected for age-related change. Relatively poor outcomes defined as important, included general health and social participation for the elderly, and the latter for those having had COVID-19. In conclusion, this study found no evidence for a decline in important aspects of adult general population health in Norway that might be attributed to the pandemic at approximately 9 months.