Table II.
Summary of findings
| PRP injections compared with control interventions for alopecia Patients or population: individuals with alopecia (AGA or AA) Settings: outpatients Intervention: PRP injection Comparison: saline placebo or triamcinolone injection for outpatients | ||||||
|---|---|---|---|---|---|---|
| Outcomes | Illustrative comparative risks* (95 % CI) | Relative effect (95% CI) | N. of participants (studies) | Quality of the evidence (GRADE) | Comments | |
| Assumed risk | Corresponding risk | |||||
| Placebo | PRP | |||||
| Hair density hairs/cm2 (3–6 months) | The mean hair density ranged across control groups from 32 to 168 hairs/cm2 | The mean hair density in the intervention groups was 145 hairs/cm2 (from 63 to 187) | Mean difference: 25.6 (from 2.62 to 48.57) | 308 (7) | ⊕⊕⊝⊝ low 1 |
On average, use of PRP injection compared with saline injection may increase hair density over a medium-term follow-up period |
| Hair count Hairs/0.65 cm2 | The mean hair count ranged across control groups from 87.9 to 112 hairs/0.65 cm2 | The mean hair count in the intervention groups was 119.6 hairs/0.65 cm2/(from 115 to 123) | Mean difference: 18.4 (from −2.86 to 39.8) | 110 (3) | ⊕⊝⊝⊝ very low2 |
On average, it is unclear whether or not use of PRP injection compared with placebo increases the mean hair count |
| Triamcinolone | PRP | |||||
| Hair regrowth (% of pts) - (rate of subjects with substantial improvement as measured by regrowth grading systems) (from 3 to 12 months) | 61 per 100 | 64 per 100 (from 58 to 65) | Risk difference 0.03 (from −0.35 to 0.42) | 202 (4) | ⊕⊝⊝⊝ very low2 |
On average, it is unclear whether or not use of PRP injection compared with triamcinolone injection increases the rate of subjects with hair regrowht over a follow-up period of 3–12 months |
| Adverse events | In the majority of the included studies, adverse events were not included among the predefined outcomes, and the reporting was incomplete and inadequate. | ⊕⊕⊝⊝ low3 |
No serious adverse events were reported, but the risk of reporting bias and imprecision should be taken into account. For less serious adverse events (e.g., pain at the injection site) it is not clear if their prevalence is increased or not in PRP recipients compared to recipients of injected controls. | |||
GRADE Working Group grades of evidence
High quality: Further research is very unlikely to change our confidence in the estimate of effect.
Moderate quality: Further research is likely to have an important impact on our confidence in the estimate of effect and may change the estimate.
Low quality: Further research is very likely to have an important impact on our confidence in the estimate of effect and is likely to change the estimate.
Very low quality: We are very uncertain about the estimate.
Downgraded for risk of bias and inconsistency (due to heterogeneeity, I2=94).
Downgraded for risk of bias, inconsistency (due to heterogeneeity, I2=90) and imprecision (95% CI includes line of no effect).
Downgraded twice for risk of bias (particularly reporting bias) and for serious imprecision (no events) reflecting the inadequate numbers to detect rare events.
AGA: androgenetic alopecia; AA: alopecia areata; PRP: platelet-rich plasma; CI: confidence interval.