Interview with Tainya Clarke: Latest Quarterly NHIS Key Health Indicator Estimates

HOST:  This week NCHS released its latest quarterly estimates on a number of key health indicators from the National Health Interview Survey, one of the oldest health surveys in US history dating back to 1957. This latest quarterly release covers the period up to the midpoint of 2020.  Health data from NHIS have always been driven by the types of questions asked in this traditionally in-person survey and in order to improve the quality of data the survey has been redesigned on occasion over the years, most recently in 2019. Tainya Clarke, an epidemiologist with the survey, elaborates:

TAINYA CLARKE:   The NHIS underwent a survey redesign to better meet the needs of data users.  Some questions were dropped from the survey, new questions were added, and some question text or the order they appear changed.  All these changes mean that the NHIS survey for 2019 going forward is quite distinct from the past survey.  In addition to the questionnaire design, changes made to the weighting approach have the potential to impact direct comparisons between the estimates for 2019 to June 2020 and earlier years.  Because of this we have not examined trends prior to 2019 in this release.

HOST:  The last time the NHIS was redesigned was in 1997.  That redesign laid the foundation for the creation of the early release program, which features quarterly preliminary estimates on a number of high profile health topics.  The 2019 redesign introduced several new topics to the survey.  However, the arrival of the pandemic in 2020 forced more changes to the way the survey operates, which in turn has had an impact on response rates:

TAINYA CLARKE:    Due to the current pandemic and the need for physical distancing, in quarter two we switched to a telephone-only approach, and in quarter three and four a telephone-first approach and followed up in person for households with no response or without a listed telephone contact.   We may have some new questions on COVID-19 and related health behaviors added in the future early releases.  So we’re not quite sure what those questions will be – only time will tell.

HOST:  In recent years this release has switched from a publication-based format to an interactive web-based data visualization format.  But there remains a gold mine of important data topics in this quarterly release.  For example, hypertension among adults is now being tracked, which is important particularly now during the pandemic with high blood pressure being a major risk factor for people with COVID-19.

TAINYA CLARKE:   The early release data in 2019 and the first half of 2020 showed that about 1/4 of US adults have been diagnosed with hypertension in the past 12 months, and the prevalence is highest among non-Hispanic Blacks, with more than one in three having hypertension in the past 12 months.

HOST:  The NHIS has tracked cigarette smoking among adults since the 1960s, and has documented along running decline in the percentage of adults who smoke.  Cigarette smoking is also one of the topics featured in this week’s new quarterly release showing that an all-time low of 12.2% of American adults were current cigarette smokers in Quarter Two of 2020.  And recently, the NHIS has added E-cigarette use to this quarterly release.

TAINYA CLARKE:   In 2019 we had approximately 4.4% of adults using E-cigarettes.  The percentage is even lower in January to June 2020 at 3.6%.

HOST:  Some of these second quarter estimates from 2020 may indeed reflect the impact of the pandemic on the country.  However, many of the survey questions are based on the past 12 months, so any direct connection to the pandemic is inconclusive.  This includes the second quarter 2020 finding that a higher percentage of adults are seeking mental health counseling, as well as the fact that a lower percentage of adults visited the emergency Department during this period. Another important measure featured in this quarterly release is flu vaccination.  Nearly half of adults reported they received a flu vaccine, according to data from the second quarter of 2020.  But Tainya Clarke says some context is needed when interpreting those immunization numbers.

TAINYA CLARKE:   I think I want to point out that even though this is almost 50% – and to some people that may seem like a large percentage – the target for vaccinating adults against influenza is much higher.  It’s closer to 70% for HP 2020 – that’s a Healthy People 2020 initiative.  And although that initiative is targeted at seasonal flu, we really hope to see a larger percentage of the U.S. adult population receiving more flu vaccines going forward.

HOST:  The latest quarterly release of data from the NHIS also includes new data on health insurance coverage in America.  During the first half of 2020, over 30 million Americans – or 9.4% – were uninsured at the time they were interviewed as part of the survey.  This proportion of the population who had no insurance includes over 13% of those ages 18 to 64.  In this age group, a little more than one in five had public health insurance and a little more than 2/3 had private insurance.  The poor or near poor in this age group were more likely to be uninsured than those who are not poor. Hispanic adults in this 18 to 64 age group were twice as likely to be uninsured as non-Hispanic black adults and nearly three times as likely as non-Hispanic white or non-Hispanic Asian adults.  Among children under age 18, less than 5% were uninsured, and among those who did have insurance over 41% had public coverage and over 56% had private coverage.

HOST:  Our thanks to Tainya Clarke of the National Health Interview Survey for joining us on this edition of “Statcast.”  Join us next week for a special segment on data related to the pandemic’s impact on life expectancy.