What a registry recruitment study found about calls versus texts

Latino participants are underrepresented in smoking cessation clinical trials, a well-documented gap that recruitment strategy alone can't fully close but can meaningfully narrow. A study addressing this directly recruited from an emergency department patient registry of 1,680 potential participants, testing two outreach channels, phone calls and text messages, and found a result worth examining closely rather than assuming.

The gap between channels was large, not marginal

Of the registry, 1,132 people were contacted by phone call and 548 by text message. The response rate for calls was 26.4%, compared to 6.4% for texts, a statistically significant difference. That gap widened at each subsequent stage: 11.4% of call recipients expressed interest in the trial, compared to 1.8% of text recipients. Enrolment followed the same pattern, 1.1% from calls versus 0.2% from texts.

At every single stage of the recruitment funnel, response, interest, and enrolment, phone calls substantially outperformed text messages for this specific population and this specific registry. That's not a marginal preference. It's close to an order-of-magnitude difference by the time you reach actual enrolment.

What didn't predict response is almost as informative as what did

The researchers also examined whether demographic and contextual factors, ethnicity, age, time of day, and week of the month, were associated with response rates. None of them were significant predictors. That's a genuinely useful negative finding: it means the channel itself, call versus text, was doing far more explanatory work than any of the more commonly assumed variables like when the outreach happened or who specifically was being contacted within this population.

That combination, a large channel effect and an absence of effect from timing or demographic subgroup, points toward something about the channel's format itself, not about who was reached or when. A phone call offers something a text can't: the chance to explain a study, answer an immediate question, and build a small amount of trust in real time, with a real person, before asking someone to commit to anything. For a population that may have limited prior engagement with clinical research and reasonable grounds for scepticism about it, that difference in format plausibly matters more than the specific hour a message arrives.

Why "feasible" and "effective" aren't the same conclusion

The study's own framing is worth reading carefully: the researchers concluded that recruitment of Latino participants from an ED patient registry into this trial was feasible using both call and text, while also noting that enrolment overall may be low. Both things are true simultaneously, and the distinction matters for how a study team should read a result like this. Feasibility means the channel can work at all, that it's possible to reach and enrol people this way. It doesn't mean the absolute yield will be high, and 1.1% enrolment from an initial contact list is a genuinely low conversion rate in absolute terms, even though it dramatically outperformed the text-based alternative on a relative basis.

A study relying on registry-based outreach as a primary recruitment strategy for an underrepresented population needs both numbers in view: which channel converts better relative to the alternative, and what absolute volume of outreach will be needed to hit an actual enrolment target given how low that conversion rate is likely to be either way.

What this means for planning outreach to underrepresented populations

A few practical points follow from this specific, if narrow, dataset:

• Don't assume text-based or digital-first outreach is automatically more effective, or even equally effective, across every population. The channel effect found here was large enough to change which strategy should get the bulk of recruitment resource and effort.
• A human touchpoint early in the process may carry real weight for populations with less established trust in clinical research. The scale of the call-versus-text gap is consistent with format, not timing or demographics, driving the difference.
• Plan recruitment volume around realistic conversion rates, not the headline response rate. Even the better-performing channel here converted at just over 1%, meaning a meaningful enrolment target requires a correspondingly large initial outreach list.
• Treat this as one data point on one population and one registry, not a universal rule. The specific finding here, calls beating texts substantially for Latino participants recruited via an ED registry into a smoking cessation trial, is a genuine and useful signal for similar contexts, but recruitment channel effectiveness plausibly varies by population, condition, and setting in ways worth testing directly rather than assuming transfer automatically.

The broader lesson is a caution against a one-size-fits-all recruitment channel strategy, particularly when the explicit goal is reaching a population that's been historically underrepresented. The channel that's cheapest or most scalable in the abstract isn't necessarily the one that will actually work for the specific population a study is trying to reach.