Since September, I’ve asked Vox’s readers to tell me their stories about drug addiction treatment for our Rehab Racket project. In less than four months, we’ve gotten a lot of responses — now more than 1,000.

From all of these experiences, one theme emerges: Addiction treatment in the US is expensive, hard to navigate, and far too often fails people. In the middle of an opioid epidemic that’s helped lead to more than 700,000 drug overdose deaths since 1999, America’s main defense against addiction is deeply flawed.

The stories we’ve published so far speak to these problems. Kim and Tim Blake spent more than $110,000 on treatment for their oldest son, yet much of the treatment was unhelpful and he died anyway. Michel Cote’s daughters went through $200,000 worth of treatment over a decade before they finally found something that worked for them. Nan Warren faces financial ruin after she lost her oldest son to addiction and has spent years trying to avoid the same fate for her surviving daughter.

Health insurance alone is not enough to protect patients from high costs and low quality. Maureen O’Reilly lost her son to addiction after their health insurance plan wouldn’t cover addiction care near home and he was sent to shoddy treatment facilities — some of which were later shut down — in Florida.

Here are four lessons from the project so far -

1) Poor insurance coverage leads to high addiction treatment costs

This is a big problem nationwide: Based on the National Survey on Drug Use and Health, federal researchers estimated that roughly 314,000 people in the US in 2018 needed drug addiction treatment but couldn’t get it because they didn’t have health coverage and couldn’t afford the costs. About 100,000 couldn’t get it because, while they had health coverage, it didn’t cover treatment at all or it didn’t cover the full cost. (There’s some overlap between the groups because participants were able to select multiple responses.)

2) We know disturbingly little about addiction treatment in America

While reporting on addiction treatment in the US and asking experts about the evidence for addiction care, there has been one answer I’ve gotten used to hearing a lot: “I don’t know.”

It was a common response when I asked if certain addiction treatments worked. Many facilities, for example, now use equine therapy, in which patients connect with horses. But we have next to no research on whether this works. The same is true for wilderness therapy that emphasizes outdoors activities, which also has little reliable scientific evidence behind it.

3) We don’t make good use of what we do know about addiction treatment

For example, the research shows that medications for opioid addiction — methadone, buprenorphine, and naltrexone — are very effective: Studies show they cut the mortality rate among opioid addiction patients by half or more and keep people in treatment better than non-medication approaches.

Yet in the US, the majority of addiction treatment facilities don’t offer any medications. According to federal data, only 42 percent of the nearly 15,000 facilities tracked by the Substance Abuse and Mental Health Services Administration (SAMHSA) provide any type of medication for opioid addiction. Less than 3 percent offer all three federally approved medications.

4) Stigma is a huge issue

When writing about anything addiction-related, there’s an explanation I can expect for just about any problem: stigma. Indeed, it’s the thing that ties the lessons on this list together.

This has stuck with me ever since I went to Vermont in 2017 to see how the state built up its addiction treatment system. When I asked officials about the hurdles to building up the new system of care, I expected to hear a lot about money (a common problem in policymaking). But officials told me, in fact, that money wasn’t that big of a deal. Instead, the main barrier was stigma around addiction, fueled by the notions that addiction is a moral issue — not a health issue — and people with addiction don’t deserve public resources. Once that stigma was overcome, the money came easily.