Table 2.
Treatment protocols for included trials
| First author [Ref.], year | PRP treatment sessions | Interval between sessions | Total follow-up period | Description of PRP application |
|---|---|---|---|---|
| Anitua [29], 2017 | 5 | 1 mo for first 4 sessions; final session 7 mos after start point | 1 year | Intradermal injections of PRGF into hair-depleted areas |
| Alves [33], 2016 | 3 | 1 mo | 6 mos (at 3-mo intervals) | Injections (0.15 mL/cm2) within four 1×1 cm selected circular areas of the frontal & occipital scalp (marked with a dot tattoo) depending on the treatment-designated side of the scalp (vs. control side of the scalp received placebo (normal saline); no local anesthesia was used |
| Gentile [34], 2015 | 3 | 30 days | 2 years (at baseline and 2, 6, 12, 16, and 23 mos after initial treatment) | Interfollicular injections of PRP (0.1 mL/cm2) within 2 of the 4 selected areas of the scalp (physiologic solution into the other 2 areas), after cleaning skin with 70% alcohol; target areas were marked with semi-permanent tattoos for subsequent treatment and evaluation; local anesthesia was not used |
| Cervelli [28], 2014 | 3 | 1 mo | 1 year (at baseline and 14 wks, 6 mos, and 12 mos after initial treatment) | Intradermal injections (0.1 mL/cm2) into 2 of the 4 selected halves (e.g. frontal or parietal) (placebo was injected into the other 2 halves) after the scalp was cleansed with 70% alcohol; local anesthesia was not used |
| Singhal [12], 2015 | 4 | 2–3 wks | 3 mos (at 1-wk intervals) | Injections using nappage technique (multiple small injections in linear pattern 1 cm apart) after area was cleansed with spirit and povidone-iodine |
| Gupta [32], 2017 | 6 | 15 days | 6 mos | Scalp was activated by microneedling; then, PRP was massaged into the vertex of the scalp (10 cm from the glabella) |
| Schiavone [36], 2014 | 2 | 3 mos | 6 mos | After local anesthesia (xylocaine 1%, with adrenaline 1:100,000) was administered, cutaneous inflammation was induced via application of gentle pressure using 1.0-mm-deep Scalproller to favor activation of injected platelets; then, superficial injections were administered 1 cm apart |
| Gkini [40], 2014 | 3 (+1 booster) | 21 days (booster 6 mos after onset) | 1 year | Injections (0.05–0.1 mL/cm2) were performed using nappage technique in affected areas to a depth of 1.5–2.5 mm; a specific area was checked at all times by defining a “V” (Kang's point) as proposed by Lee et al. [43] |
| Khatu [35], 2014 | 4 | 2 wks | 12 wks | Nappage technique injections (2–3 ml) into a prefixed 1 1 cm squared area over the right parietal area; anesthetic cream was applied before each treatment after cleaning the skin with cetavlon, spirit, and povidoneiodine |
| Takikawa [37], 2011 | 5 | 2–3 wks | 12 wks | Subcutaneous injection (3 mL) into selected 1 × 1 cm areas measured from the nasal tip and upper part of the auricular base |
| Puig [30], 2016 | 1 | n.a. | 26 wks (at 4-wk intervals) | Single subcutaneous injection within the 4 cm2 area in the central scalp (termed the “hair check data box”), after anesthesia (2% lidocaine and 0.5% bupivacaine) was administered |
| Mapar [31], 2016 | 2 | 1 mo | 6 mos (at 1, 3, and 6 mos after initial treatment) | Injections (1.5 mL of PRP) within one of two 2.5 × 2.5 cm square regions, at least 3 cm apart, in the scalp randomly assigned to be a case square (control square received 1.5 mL of normal saline); randomization of case and control squares was performed using a random number table; iron oxide- and titanium dioxide-containing substances were used to tattoo the corners of the squares |
mos, months; wks, weeks.