The latest enrollment numbers publicized by New York’s Obamacare exchange paint an incomplete and misleading picture of what’s really happening in the state’s health insurance marketplace.

The Health Department announced on Friday that 3.5 million people had signed up for coverage through its insurance exchange, known as the New York State of Health. The figure was described as a 22 percent increase compared to last year, with a month left to go in the open enrollment period for 2017.

This resulted, understandably, in headlines such as “New Yorkers flock to health care exchange,” “Obamacare numbers soar in N.Y.,” and “NY Affordable Care Act at record high.”

In fact, however, New York’s overall Obamacare-related enrollment numbers did not soar. The change since the close of the last enrollment period was probably closer to 2 percent than 22 percent.

The reason for the discrepancy is that DOH’s release counted only sign-ups through the exchange, which handles less than half of the enrollment for the relevant programs. When off-exchange enrollment is included, the picture changes dramatically, as shown in the chart below.

On-exchange enrollment for Medicaid, for example, jumped by almost 366,000, or 19 percent, since the last enrollment period. But overall enrollment in the program was down by 111,000, or 2 percent, as of October. This is because a greater share of people are using the exchange to enroll in the program even as fewer people signed up. (Since Medicaid enrollment is continuous, with no “open enrollment” period, this number is unlikely to have changed significantly in the last two months.)

Similarly, Child Health Plus enrollment was up by about 70,000 on the exchange, but 44,000 overall.

For the two remaining programs, on-exchange and overall enrollment are the same. The Essential Plan, a very low-cost option for people earning up to double the federal poverty level, was up by a substantial 68 percent. Meanwhile, the private plans sold through the exchange, known as qualified health plans, were down by 20 percent as of December 24 – possibly signaling the continuation of a worrying trend.

Going forward, the Health Department should include off-exchange data in its enrollment reports, so that ordinary New Yorkers can better understand the big picture.