Health Survey for England, 2021 part 1

The Health Survey for England (HSE) is designed to estimate the proportion of people in England who have health conditions, and the prevalence of risk factors and behaviours associated with certain health conditions among the population and to monitor trends. It provides information about adults aged 16 and over, and children aged 0 to 15, living in private households in England. 

Each survey in the series includes core questions, and measurements such as blood pressure, height and weight measurements and analysis of blood and saliva samples. In addition, there are modules of questions on specific issues that vary from year to year.

Owing to the Covid-19 pandemic, the fieldwork for the 2020 HSE ceased in March. In 2021, the data collection approach differed from previous years. This included a change in mode, from face-to-face interviewer visits to remote telephone and video interviews, to limit contact between participants and interviewers. Full details can be found in the HSE 2021 Methods report.

A total of 5,880 adults (aged 16 and over) and 1,240 children (aged 0 to 15) were interviewed in the 2021 survey. 1,705 adults and 250 children had a nurse visit.

The 2021 report covers Overweight and obesity and Health-related behaviours. Findings are for adults only; findings about children are not included because of low sample numbers within different age groups.

The usual Health Survey for England (HSE) data collection methodology was adapted in 2021 to reflect restrictions caused by the COVID-19 pandemic and the sensitivities of potential participants. The main change was that interviews were carried out by telephone, rather than in person. Estimates of height and weight were based on self-report rather than in-home measurement, as in all previous HSE survey years. The differences between the 2021 survey and previous years are summarised in the HSE 2021 Methods report.

The household response rate was also lower than usual; 32% of eligible households participated, compared with 60% in 2019, the last full survey year. For more information on household and individual response to the survey, see HSE 2021 Methods report.

Because of these differences, findings from 2021 are not directly comparable with those from previous years. Past trends are discussed in the text and shown in the tables. However, any apparent differences or similarities between these and 2021 estimates may be influenced by how the surveys were carried out, so caution is advised if making inferences about any apparent changes in prevalence over time. 

The Health Survey for England, in common with other surveys, collects information from a sample of the population. The sample is designed to represent the whole population as accurately as possible within practical constraints, such as time and cost. Consequently, statistics based on the survey are estimates, rather than precise figures, and are subject to a margin of error, shown as a 95% confidence interval. 

For example, the survey estimate might be 24% with a 95% confidence interval of 22% to 26%. A different sample might have given a different estimate, but we expect that the true value of the statistic in the population would be within the range given by the 95% confidence interval in 95 cases out of 100.

Where differences are commented on in this report, these reflect the same degree of certainty that these differences are real, and not just within the margins of sampling error. These differences can be described as statistically significant implying no more than a 5% chance that any reported difference is not a real one but a consequence of sampling error. Statistical significance does not imply substantive importance; differences that are statistically significant are not necessarily meaningful or relevant. 

Confidence intervals are shown for key statistics within this report in the accompanying Excel tables. Confidence intervals are affected by the size of the sample on which the estimate is based. Generally, the larger the sample, the smaller the confidence interval, and hence the more precise the estimate. 

Adult data within this report have been age-standardised to allow comparisons between groups after adjusting for the effects of any differences in their age distributions. When different sub-groups are compared in respect of a variable on which age has an important influence, any differences in age distributions between these sub-groups are likely to affect the observed differences in the proportions of interest. For information about the method used, see HSE 2021 Methods report.

Estimates presented in the text are rounded to the nearest whole number. Where categories are combined the sum of two estimates may sometimes appear to be greater or less than expected. This reflects the effect of rounding; for example, estimates of 10.6% and 12.7% would round respectively to 11% and 13%, but the sum (23.3%) will round to 23% rather than 24%.

The charts are based on unrounded estimates. Values given in the text may appear different in the corresponding chart. For example, an estimate of 10% in the text may represent a value between 9.5% and 10.4%.