In a recent conference call with investment analysts, the CFO of a company said:

"Bad debt expense as a percentage of revenues was 4.4%, 20 basis points better year-over-year but 80 basis points higher than the fourth quarter of 2016. As a reminder, bad debt expense rate typically increases sequentially in the first quarter due to the reset of patients' health insurance deductibles at the beginning of the year. As in prior years, we expect the bad debt rate to improve gradually throughout the year. Note that the year-over-year compare was also negatively impacted by the fact that our products business had a lower associated bad debt rate."

Why is it suggested that bad debt expense is typically higher in the first quarter than it is in later quarters? What is the economic rationale?

Why do investors care about a company's bad debt rate and why was it necessary to address this with the analysts on this conference call?