What does illness-especially chronic illness-cost? Can we meaningfully estimate total cost? We most commonly consider direct health care costs, especially hospital care and prescription pharmaceuticals. Estimating even these costs can be quite difficult. However, direct health care costs may represent only a fraction of the costs of illness, leading to underestimation of societal economic burden. Published estimates of cost may not include all costs of illness, leaving experienced readers of the literature unsure as to whether all costs are included and which may be left out. One specific cost of illness that has been discussed but rarely estimated is lost labor productivity.Luo et al 1 estimate lost labor productivity elsewhere in JAMA Network Open. The source of data was the 2019 Panels Study of Income Dynamics (PSID), a long-standing survey (begun in 1968) of households in the US designed to assess the dynamics of a nationally representative sample of income and poverty. 2 Since 1997, PSID has provided cross-sectional weights calibrated to US population characteristics, and since 1999, data on chronic diseases. The current study 1 uses the 2019 survey, which includes 9569 families and 26 084 individuals. This study focuses on a reference person in the survey and their spouses. The study is limited to people aged 18 to 64 years, when they are most likely to be in the workforce. Labor income for the year before the survey included wages and salary, bonuses, overtime, tips, commission, professional practice, additional jobs, and miscellaneous. Heart disease and stroke were coded as present if the participant responded "yes" to the question of whether a health care clinician had ever told them they had the condition. There were 12 166 participants, with a prevalence of prior heart disease and stroke of 3.7% and 1.7% respectively.