The link between health insurance and employment is one of the most salient features of the American health care system, but it's exact impacts are a bit difficult to fully understand. Cathy Bradley, David Neumark, and Scott Barkowski have an interesting study looking at married women who've been diagnosed with breast cancer:
Employment-contingent health insurance creates incentives for ill workers to remain employed at a sufficient level (usually full-time) to maintain access to health insurance coverage. We study employed married women, newly diagnosed with breast cancer, comparing labor supply responses to breast cancer diagnoses between women dependent on their own employment for health insurance and women with access to health insurance through their spouse’s employer. We find evidence that women more dependent on their own job for health insurance reduce their labor supply by less after a diagnosis of breast cancer – the estimate difference is about 5.5 to 7 percent. Women’s subjective responses to questions about working more to maintain health insurance are consistent with the conclusions from observed behavior.
An important piece of background here is that empirical examinations of tax issues tend to show that married women's labor supply is much more elastic than the labor supply of single women or men. The issue, presumably, is that it's more socially acceptable for a married woman to not be working than it is for a married man. Anyway, the finding here is that a married woman with a job who gets breast cancer but is capable of getting health insurance through her husband is more likely to drop out of the workforce post-diagnosis than is a married woman who needs the job to maintain her insurance.
The implication is that if we had a single-payer health care system, we'd see somewhat fewer married women with serious medical ailments in the workforce.