§ R.2 · Reference field guide

Reading research.

Most patients can't tell a registry write-up from an RCT, and the difference matters more than almost anything else on the page. This is the field guide: what the abbreviations mean, which sentences carry the weight, and the phrasing that should make you slow down.

Fig. R.2.0 · A study's design line, decoded
Phase 2, randomized, double-blind, placebo-controlled trial of UC-MSCs in 82 RA patients refractory to methotrexate.
Phase
Where on the
evidence pyramid.
Assignment
How patients
got the arm.
Bias control
Who knew what
during follow-up.
Comparator
What the effect
is measured against.
Sample
How much noise
swamps the signal.
Five words tell you the tier. Everything else in the abstract is context for these five. The rest of this guide is how to read them.

A study is not a study is not a study.

If you spend even an hour reading "the research" on cell therapy, you will find a study supporting almost any claim. And a study contradicting it. That's not because the field is incoherent. It's because "study" is a wildly elastic word and most of the writing patients encounter uses it without distinction. A 12-patient case series and a 1,200-patient randomized trial both get called "a study." They carry vastly different weight.

This page is the smallest amount of context a non-clinician patient needs to read a stem-cell paper and walk away with a calibrated belief about what it actually shows. Three things in order: the hierarchy of evidence (which study designs carry more weight), the anatomy of an abstract (which sentences are the load-bearing ones), and a short list of red-flag phrases that should make you slow down.

§ Evidence tiers

5 levels.

Meta-analysis > RCT > cohort > case series > expert opinion. A claim's weight is bounded by the strongest source supporting it.

§ Sentences that matter

5 load-bearing.

Design, sample size, control, primary endpoint, and statistical result. Everything else is context.

§ Red-flag phrases

8 to slow on.

"Patients reported improvement," "many of our patients," "shown to", phrasing without a method underneath.

Tiers 01 The evidence hierarchy

Not all studies are equally heavy.

Clinicians read papers through a near-automatic mental filter that weighs design before content. A claim from a meta-analysis lands differently than the same sentence from a single-arm case series, even when the words are identical. The pyramid below is the version of that filter you can hold in your head.

Figure R.2.1 · Hierarchy of evidence

Five tiers, roughly to scale.

1
Meta-analysis / systematic review
Pooled data across multiple RCTs, with formal heterogeneity testing.
Heaviest
2
Randomized controlled trial (RCT)
Prospective; randomized assignment; ideally double-blinded with placebo.
Strong
3
Prospective cohort
Group followed forward in time; no randomization. Confounders not neutralized by design.
Moderate
4
Case series / registry
"We treated N patients; here's what we observed." No comparator. Selection bias unbounded.
Weak
5
Expert opinion / single case report
Anecdote with credentials. Useful for hypothesis generation, not for treatment decisions.
Weakest

The thing to know is that most of the cell-therapy literature for non-orthopedic indications is at tier 3 or 4. Some published autism papers from named clinics are registry write-ups. Some MS papers are small prospective cohorts. RCTs exist for graft-versus-host, ARDS, and a handful of others, but they are the exception. When a clinic says "we have published research," ask which tier.

Figure R.2.1.1 · What N= actually looks like

Sample size, to scale.

N = 18
Pilot / case series

What it can find: only enormous effects. A study this small cannot detect a 20% improvement; the noise is louder than the signal. Useful for safety screening and hypothesis generation. Not useful for "this treatment works" claims.

N = 200
Phase 2

What it can find: moderate effects with reasonable certainty. A well-designed N=200 RCT can detect a 15–20% response-rate difference. Confidence intervals still wide enough that the result needs phase 3 confirmation.

N = 2,000
Phase 3 / registration

What it can find: small effects with high certainty and rare adverse events. The N at which regulators approve drugs. The cell-therapy literature has almost none of this for non-orthopedic indications.

Anatomy 02§ How to read an abstract

Five sentences do all the work.

A typical abstract is 250 words and looks dense. It isn't, about 80% of it is context. Five sentences carry the actual weight. If you can find these five and read them carefully, you have read the paper for almost all decision purposes.

Figure R.2.2 · An abstract, marked up

Five sentences worth slowing down on, highlighted in a sample abstract.

Background. Mesenchymal stromal cells (MSCs) have shown immunomodulatory promise across autoimmune indications, but evidence in moderate-to-severe rheumatoid arthritis (RA) remains limited. We conducted a phase-2 randomized, double-blind, placebo-controlled trial of allogeneic UC-MSCs in RA patients refractory to methotrexate. Methods. Eighty-two adults (ages 35–65) with DAS28 >5.1 were randomized 1:1 to a single IV infusion of 1×10⁸ UC-MSCs or saline placebo. The primary endpoint was DAS28 change from baseline at 24 weeks; secondary endpoints included ACR20/50/70 response, serum CRP, and patient-reported outcomes. Results. At 24 weeks, mean DAS28 decreased by 1.8 (SD 0.9) in the UC-MSC arm versus 0.7 (SD 1.1) in placebo (between-group difference 1.1; 95% CI 0.6–1.6; p<0.001). ACR20 was met by 64% vs. 28%. No grade ≥3 treatment-related adverse events. UC-MSCs were well tolerated and associated with significant disease-activity reduction; larger confirmatory trials are warranted.
▶ Design
"Phase-2 randomized, double-blind, placebo-controlled." This is the line that tells you which tier of the pyramid you're on. Three words to look for: randomized, blinded, controlled. Missing any one demotes the study by a tier. Missing all three (e.g. "single-arm open-label") puts you at tier 4.
▶ Sample
"Eighty-two adults... randomized 1:1." Sample size and randomization ratio. Under 30 patients per arm is exploratory. The ratio tells you whether the comparator group is the same size, important for the stats.
▶ Primary endpoint
"DAS28 change from baseline at 24 weeks." The one outcome the study was built to measure. Secondary endpoints are interesting; only the primary one is binding for the study's claim. If the primary endpoint isn't met but a secondary one is, that's a much weaker result than the abstract may make it sound.
▶ Effect size + p-value
"Between-group difference 1.1; 95% CI 0.6–1.6; p<0.001." Three things in that sentence: the size of the effect (1.1 DAS28 points), the confidence interval (0.6–1.6, wider intervals = less certainty), and the p-value (<0.001 here is strong; >0.05 is "not statistically significant"). A small p-value with a tiny effect size is still a tiny effect size.
▶ The authors' claim
"UC-MSCs were well tolerated and associated with significant disease-activity reduction." Note "associated with". the careful version of the claim. The press release will say "shown to reduce" or "proven to treat." That escalation usually happens between the abstract and the marketing.
▶ The honest hedge
"Larger confirmatory trials are warranted." This sentence is almost always in the abstract of any honest phase-2 result. It's the authors saying: this is real, but it isn't yet definitive. A paper that doesn't include some version of this sentence is doing something rhetorically odd.
Figure R.2.2.1 · How to read a confidence interval

The width of the bar is the certainty.

−1
0
1
2
3
Tight CI, real effect
1.1 [0.6 – 1.6]
Strong. CI sits entirely above zero; effect is real and reasonably precise.
Wide CI, same point estimate
1.1 [0.1 – 2.1]
Weaker. Same effect on paper, but the true value could be anywhere from "barely real" to "twice as big." Usually smaller N.
CI crosses zero
0.8 [−0.3 – 1.9]
Not significant. The CI includes zero, no effect is among the plausible truths. Press release may still call this "trending toward benefit." It isn't.
Cheat 03 The abbreviation cheat sheet

The two-dozen abbreviations that come up.

What follows is not a complete list, there are hundreds, but these are the ones you will see repeatedly in cell-therapy abstracts. The "what it tells you" column is the practical use: what the abbreviation means about a paper's strength when you see it in the design line.

Figure R.2.3 · Abbreviations you'll see in cell-therapy abstracts
Abbrev.
What it stands for
What it tells you
RCT
Randomized Controlled TrialThe gold standard.
Strong evidenceIf "double-blind, placebo-controlled" follows, even stronger.
DBRCT
Double-Blind RCTNeither patient nor evaluator knows assignment.
Strongest single-trial designBias from expectation and assessment both controlled.
Open-label
Both parties know who got what.Often paired with "single-arm."
Demotes the studyPlacebo-effect and assessment bias both uncontrolled.
Phase 1
Safety / dose-findingUsually <30 patients.
Not an efficacy claimIf "phase 1" results are pitched as efficacy, that's overreach.
Phase 2
Efficacy signal-seekingTypically 100–300 patients.
Hypothesis-generatingReal signal possible; needs phase 3 to confirm.
Phase 3
ConfirmatoryTypically 500–3,000 patients.
Regulatory-quality evidenceThe phase used for drug approval.
ITT
Intent-To-TreatAnalysis includes all randomized patients.
Conservative analysisThe honest way to handle dropouts. "Per-protocol" excludes them, inflates apparent effect.
CI
Confidence IntervalThe plausible range of the true effect.
Tighter = betterIf the CI crosses zero, the effect is not statistically distinguishable from no effect.
p < 0.05
Conventional statistical significance threshold.5% chance the result is noise.
Necessary, not sufficientA tiny effect with a small p-value is still a tiny effect.
SAE
Serious Adverse EventHospitalization, death, life-threatening event.
Safety signalThe SAE count in the treatment arm vs. control arm is the safety read.
N=
Sample size"N=12" = twelve patients.
The single most undersold numberAn N<20 study cannot find anything but enormous effects.
f/u
Follow-up durationHow long patients were tracked.
Short f/u limits claimsSix-month f/u cannot speak to durability at 24 months.
Flags 04·Phrases that should slow you down

Eight constructions that almost always mean something weaker than they sound.

These are not lies. They are rhetorical hedges phrasings that let the writer claim something without saying it. Every one of them can be perfectly accurate; what they almost never are is what the casual reader takes them to mean.

Figure R.2.4 · Eight phrases to slow down on

If you see one of these, look for the method.

Patients reported improvement

Translates to: we asked them how they felt. No objective measure, no control group. This is a sentence about self-report, not a sentence about effect.

Many of our patients have seen

Translates to: we have not counted. "Many" is unfalsifiable. The honest version is "in N=X patients, Y showed improvement" with both numbers.

Shown to be effective

Translates to: in some study somewhere. Ask: shown by whom, in what design, with how many patients, against what comparator?

Promising preliminary results

Translates to: phase 1 or single-arm phase 2 data. "Preliminary" is the giveaway. Real efficacy claims don't need the word.

In our experience

Translates to: we have not published this. Clinical experience is real and useful, but it isn't evidence at the tier the abstract is pretending to occupy.

Statistically significant

Translates to: the result is unlikely to be random noise. Says nothing about effect size. A 0.2-point change on a 10-point scale can be statistically significant and clinically meaningless.

Comparable to

Translates to: we did not run a head-to-head. "Comparable to" almost always means "in a different study with a different population, the numbers look similar." That isn't equivalence.

Well-tolerated

Translates to: there was no acute disaster. Says nothing about long-term safety or about adverse events below the SAE threshold. Look for the explicit SAE count.

Figure R.2.4.1 · The same result, three rooms

How one finding escalates from abstract to ad copy.

The published abstract Peer-reviewed
UC-MSCs were well tolerated and associated with significant disease-activity reduction at 24 weeks; larger confirmatory trials are warranted.
Accurate
The university press release PR office, not authors
New trial shows stem cell therapy reduces rheumatoid arthritis activity, a promising step toward a new treatment option.
Drifting
The clinic marketing page Unaffiliated with the study
Stem cells have been proven to treat rheumatoid arthritis. Our patients report life-changing results.
Overreach
Practice 05? How to use this on our own claims

Apply this to us too.

We do not yet have peer-reviewed publications. Section 6.2 says this explicitly. Stem Cell Institute Panama has multiple peer-reviewed papers; we have none to date. By the hierarchy on this page, that puts us at tier 5 for any clinical-outcome claim. We try to compensate by being precise about manufacturing (which has objective release tests) and silent about outcomes (which we can't compare across patient populations).

If you read elsewhere on our site that "patients reported improvement" or "many patients have seen X," that wording is broken on our end and we want to hear about it. The standard we are trying to hold ourselves to on this site is the same one we are inviting you to hold us to on the rest of the field. Write to [email protected] if you find one.

Four questions to ask any cell-therapy outcome claim.

  • What was the study design? RCT, cohort, case series, or registry. The answer should be one word. If the answer is "many studies show," ask for a citation.
  • What was the sample size, and what was the control? "N=18, no control" is a different claim than "N=200 randomized vs. placebo."
  • What was the primary endpoint, and was it met? If the primary endpoint failed but a secondary one passed, the headline result is "negative trial with a positive secondary."
  • What was the effect size (not the p-value, the effect size)? A small p-value can hide a clinically meaningless effect. Ask for the magnitude, not the significance.
The bottom line

Five tiers, five sentences, eight phrases.

Read the design line first; it bounds everything else. Find the five load-bearing sentences in the abstract (design, sample, endpoint, result, hedge) and ignore the rest until you've understood them. Treat "patients reported," "many of our," "shown to," "promising preliminary," "well-tolerated," "comparable to," "statistically significant," and "in our experience" as flags to slow down. they're often correct, almost never as strong as they read. Apply the same standard to our claims as to anyone else's.