Hematopoietic Stem Cell Transplantation for Storage Disorders: Present Status.

Storage disorders are a group of inborn errors of metabolism caused by the defective activity of lysosomal enzymes or transporters. All of these disorders have multisystem involvement with variable degrees of neurological features. Neurological manifestations are one of the most difficult aspects of treatment concerning these diseases. The available treatment modalities for some of these disorders include enzyme replacement therapy, substrate reduction therapy, hematopoietic stem cell transplantation (HSCT) and the upcoming gene therapies. As a one-time intervention, the economic feasibility of HSCT makes it an attractive option for treating these disorders, especially in lower and middle-income countries. Further, improvements in peri-transplantation medical care, better conditioning regimens and better supportive care have improved the outcomes of patients undergoing HSCT. In this review, we discuss the current evidence for HSCT in various storage disorders and its suitability as a mode of therapy for the developing world.

Autologous hematopoietic stem cell transplant at a tertiary care centre in India: achieving comparable outcomes with adaptations.

Autologous stem cell transplantation (ASCT) is the standard treatment for many high-risk solid tumors. Patients undergoing ASCT should be managed in a dedicated hematopoietic stem cell transplantation (HSCT) unit with isolation rooms, high-efficiency particulate air (HEPA) filters, and positive pressure. We report the outcomes of the first 20 pediatric patients who underwent ASCT in isolation rooms with no HEPA filters or positive pressure. Moreover, the isolation rooms were not part of a dedicated HSCT unit. Data from 20 patients were analyzed. All patients included in the study underwent ASCT after harvest and cryopreservation of the hematopoietic stem cells (HSC). Furthermore, all patients also underwent myeloablative conditioning. The most common indications for ASCT included high-risk neuroblastoma (HR-NB) (n=9) and refractory/relapsed Hodgkin's lymphoma (HL) (n=6). The median CD-34 positive HSC administered was 4.5 (0.8-21.9) million per kg. The median time to neutrophil and platelet engraftment was 16.5 (10-35) and 19 (10-87) days, respectively. Additionally, only one transplant-related mortality was observed and the mean time to discharge from the hospital was 27.6+8.3 days. The overall survival for all our patients was 75% at a median follow-up of 33.2 months (15 out of 20 patients survived), and the disease-free survival was 60% (median follow-up, 28.4 months). The overall survival for the patients with HL was 85.7% at a median of 45.3 months and for the HR-NB was 66.7% at a median of 34.9 months. This study provides evidence that ASCT can be safely performed in isolation rooms without HEPA filters and positive pressure if expertise and supportive care are available. In settings with limited resources, such a model could help establish low-cost HSCT units.

Serum Adipokines as Biomarkers for Surveillance of Metabolic Syndrome in Childhood Acute Lymphoblastic Leukemia Survivors in Low Middle-Income Countries.

BACKGROUND: Serum adipokines (leptin and adiponectin) are dysregulated before the onset of metabolic syndrome and hence may be useful biomarkers for screening of cardiometabolic late effects in childhood Acute Lymphoblastic Leukemia (cALL) survivors. METHODS: We compared serum adipokine levels between 40 cALL survivors (aged 10-18 years, >2 years from treatment completion) with similar controls. A multivariable logistic regression analysis was then done to assess the association of metabolic syndrome in cALL survivors with variables including adipokines and other metabolic parameters, demographic and treatment details, and Dual-energy X-ray absorptiometry scan-derived variables. RESULTS: Compared to controls, cALL survivors had a higher prevalence of metabolic syndrome (8/40 vs. 2/40, P = .044) and central obesity (11/40 vs. 4/40, P = 0.042). Median Serum Leptin (7.39 vs. 4.23 ng/ml, P = 0.207) levels and derived Leptin-Adiponectin Ratio (1.44 vs. 0.80, P = 0.598), were higher but not statistically different in our survivors compared to controls; Adiponectin levels were similar (6.07 vs. 5.01 µg/ml, P = 0.283). In the cALL survivors, overweight/obesity (odds ratio [OR] 21.9, P = 0.020) or higher Leptin levels (OR 1.11, P = 0.047), were independently associated with metabolic syndrome. CONCLUSIONS: Serum Leptin, independently predictive of metabolic syndrome in our cALL survivors, may be tested in larger studies to assess its utility in surveillance and initiation of early preventive measures.

Safety of Procalcitonin Guided Early Discontinuation of Antibiotic Therapy among Children Receiving Cancer Chemotherapy and Having Low-Risk Febrile Neutropenia: A Randomized Feasibility Trial (ProFenC Study).

In low-risk febrile neutropenia (LR-FN), the safety of early discontinuation of empiric antibiotics without marrow recovery is not well established. This study aimed to evaluate the safety of procalcitonin (PCT) guided early discontinuation of antibiotics in LR-FN. In this trial, children with LR-FN with an afebrile period of at least 24 h, sterile blood culture, and negative/normalized PCT were randomized at 72 h of starting antibiotics into two groups: intervention arm and standard arm. The antibiotics were stopped in the intervention arm regardless of absolute neutrophil count (ANC), while in the standard arm, antibiotics were continued for at least 7 days or until recovery of ANC (>500/mm3). The primary objective was to determine the treatment failure rates, and the secondary objective was to compare the duration of antibiotics and all-cause mortality between the two arms. A total of 46 children with LR-FN were randomized to either the intervention arm (n = 23) or the standard arm (n = 23). Treatment failure was observed in 2/23 (8.7%) of patients in the intervention arm compared to 1/23 (4.3%) in the standard arm [RR: 2 (95% CI: 0.19-20.6); p = 0.55]. The median duration of antibiotics in the intervention arm and standard arm were 3 days vs 7 days (P= <0.001). There was no mortality in this study. PCT-guided early discontinuation of empirical antibiotics in LR-FN is feasible. There was no significant difference observed in treatment failure between the early discontinuation of antibiotics vs standard therapy. The total duration of antibiotic exposure was significantly lesser in the discontinuation arm. Further, larger multicenter studies are needed to confirm the finding of this study.

Clinical presentation and outcomes of pediatric anaplastic large cell lymphoma: A tertiary center experience from India.

BACKGROUND: Anaplastic large cell lymphoma (ALCL) is an uncommon T-cell lymphoma, accounting for 10-15% of pediatric non-Hodgkin lymphoma (NHL). Outcomes of ALCL have not improved in recent years despite better chemotherapy and supportive care. This study aimed to analyze the clinical profile and outcomes of pediatric ALCL patients at our center. MATERIALS AND METHODS: Medical records of children with ALCL from July 2017 to December 2019 were reviewed. Their clinical and laboratory details were noted. The outcomes of all patients were recorded. RESULTS: Ten patients were diagnosed with ALCL during this period. The median age at diagnosis was 8 years, with 7 patients being boys. Lymph nodes were the primary site of involvement in four children. Extranodal involvement was seen in 60%. One patient had the underlying chronic granulomatous disease (CGD). Systemic (B) symptoms were seen in 70%. Three children had hemophagocytic lymphohistiocytosis (HLH) at presentation. All of them had stage-III disease. Seven patients were treated on the Berlin-Frankfurt-Münster-non-Hodgkin lymphomas (BFM-NHL) 90 protocol and three children are currently in remission. Four patients had disease relapse/progressive disease while on therapy. Three children had HLH at presentation and all had poor outcomes. CONCLUSIONS: Pediatric ALCL has diverse and atypical clinical presentation and a high index of suspicion is needed for diagnosis. ALCL is an aggressive malignancy and is responsive to multiagent chemotherapy, though survival has not improved over the past decade. The integration of novel agents may improve the outcome.

Efficacy and safety of plerixafor in pediatric cancer patients undergoing peripheral blood stem cell harvest for autologous hematopoietic stem cell transplant.

Plerixafor for peripheral blood hematopoietic stem cell (PB HSC) mobilization in children undergoing autologous hematopoietic stem cell transplantation is primarily used following failure of the initial mobilization attempt. Data on plerixafor use in pediatric patients are limited. This retrospective study conducted at a single tertiary care center in India, details the efficacy and safety of plerixafor for 10 children with relapsed/refractory solid tumors or lymphomas. High risk neuroblastomas (HR NB) underwent autologous HSCT as part of consolidation. Plerixafor was administered at a dose of 240 µg/kg body weight of the recipient, subcutaneously, approximately 11-12 h prior to harvest. Ten patients (eight males, two females), with a median age of 8 years (range 2-18 years), received plerixafor prior to PB HSC harvest. All patients were administered granulocyte colony stimulating factor (GCSF) before the administration of plerixafor. The median CD 34 count for all patients pre-plerixafor was 29/µL, nine patients exhibited higher CD 34 post plerixafor (median of 148/µL). In nine patients, the values of the CD 34 count and total leukocyte count (TLC) of the harvested product were available, and in all cases, we achieved a good yield. All patients in this study were heavily chemotherapy pre-treated, and the use of plerixafor resulted in a satisfactory yield of peripheral blood stem cells. No side effects were observed.

A randomized controlled trial to explore the safety and efficacy of irradiated buffy-coat granulocytes in pediatric patients with febrile neutropenia.

BACKGROUND: Transfusion of granulocytes obtained by apheresis is beneficial in febrile neutropenia (FN) but expensive and time-consuming. Buffy-coat-derived granulocytes could be an alternative. We studied the efficacy and safety of the administration of irradiated buffy-coat-derived granulocytes along with the standard of care in pediatric high-risk (HR) FN. METHODS: Sixty children ≤18 years with malignancy and chemotherapy-induced HR FN were randomized to either the granulocyte transfusion (GT) arm which received irradiated buffy-coat derived granulocyte transfusion along with the standard treatment or the standard treatment (ST) arm. RESULTS: Baseline characteristics, day-to-defervescence, antibiotic duration, hospital stay, and mortality were comparable between the groups. A significant difference was seen in days to achieve absolute neutrophil count (ANC) >500/mm3 in the 2 groups: 4.5 days (3-6.5) in the GT arm v/s 8 days (4-11) in the ST arm (P=0.01). CONCLUSION: Buffy-coat-derived granulocyte transfusion was safe and led to early hematological recovery but was not associated with survival benefits. Future studies with earlier initiation in the intended dose could be undertaken to generate more evidence.

Efficacy and Safety of Olanzapine for the Prevention of Chemotherapy-induced Nausea and Vomiting in Children: A Systematic Review and Meta-analysis of Randomized Controlled Trials.

Chemotherapy-induced nausea and vomiting (CINV) remain the most distressing event in patients receiving highly emetogenic chemotherapy (HEC) and moderately emetogenic chemotherapy (MEC). This meta-analysis was conducted to evaluate the efficacy and safety of olanzapine containing regimen in preventing CINV in children on HEC and MEC. We searched PubMed, Embase, and Cochrane central register of controlled trials electronic databases to identify randomized clinical trials that compared 2 groups who either got olanzapine (olanzapine group) or placebo/no olanzapine (control group) for the prevention of CINV in children. The primary outcome was to determine the efficacy of olanzapine (complete response). The secondary outcomes were nausea control, the need for rescue medications, and adverse events of olanzapine. Three randomized clinical trials (n=394 patients) were included in this meta-analysis (olanzapine group, n=194, and placebo/control group, n=200). The pooled analysis of this meta-analysis found that olanzapine had a higher complete response in all phases of emesis in the HEC group and only in the acute phase in HEC/MEC groups compared with the control group. Olanzapine had higher nausea control in all phases of HEC but no nausea control in HEC/MEC. Olanzapine also reduced the need for rescue medications. A significant number of patients in the olanzapine group experienced somnolence (grades 1 and 2), but none of the participants discontinued the study due to side effects. In conclusion, this meta-analysis showed that olanzapine significantly prevented CINV in HEC. There was also a lesser need for rescue medications in the olanzapine group. Somnolence was higher in the olanzapine group, but it was clinically insignificant.

Effect of Imatinib Mesylate on Growth in Pediatric Chronic Myeloid Leukemia: A Systematic Review and Meta-analysis.

The outcomes of pediatric chronic myeloid leukemia (CML) have improved with the use of imatinib mesylate (IM). Multiple reports of growth deceleration with IM have raised concerns, necessitating careful monitoring and evaluation in children with CML. We systematically searched the databases of PubMed, EMBASE, Scopus, CENTRAL, and conferences-abstracts, reporting the effect of IM on growth among children with CML, and published in the English language from inception till March 2022. For observational studies, the modified Newcastle Ottawa Scale was used to assess the risk of bias. Pooled estimates were derived using a random-effects meta-analysis, and heterogeneity was assessed using Cochrane Q statistic test of heterogeneity and I2 statistic. Of the 757 studies identified through electronic search, 15 (n=265) were included in the final analysis. Six studies (n=178) were included in the meta-analysis of the primary outcome. There was a significant deleterious effect of IM on height-standardized mean difference (SMD): -0.52 (95% CI: -0.76; -0.28) ( I2 =13%). The adverse effect of IM on height was significant among studies with a follow-up period <3 years [SMD: -0.66 (95% CI: -0.93, -0.40), I2 =0%, P =0.59] but not in studies with follow-up period ≥3 years [SMD: -0.26 (95% CI: -0.63, 0.11), I2 =0, P =0.44], indicating that the effect of IM on height is a short-term effect. The effect of IM on height was not dependent upon pubertal status at the initiation of therapy. Prospective studies with adequate sample size are required to confirm the findings of the effect of IM on height in children with CML.

Acute myeloid leukemia: novel mutations and their clinical implications.

Acute myeloid leukemia (AML) is a heterogenous and challenging hematological malignancy with suboptimal outcomes. The implications of advanced technologies in the genetic characterization of AML have enhanced the understanding of individualized patient risk, which has also led to the development of new therapeutic strategies. A comprehensive study of novel mutations is essential to moderate the complicacies in patient management and achieve optimal outcomes in AML. In this review, we summarized the clinical relevance of important novel mutations, including TET2, ETV6, SATB1, EZH2, PTPN11, and U2AF1, which impact the prognosis of AML. TET2 mutation can lead to DNA hypermethylation, and gene fusion, and mutation in ETV6 disrupts hematopoietic transcription machinery, SATB1 downregulation aggravates the disease, and EZH2 mutation confers resistance to chemotherapy. PTPN11 mutation influences the RAS-MAPK signaling pathway, and U2AF1 alters the splicing of downstream mRNA. The systemic influence of these mutations has adverse consequences. Therefore, extensive research on novel mutations and their mechanism of action in the pathogenesis of AML is vital. This study lays out the perspective of expanding the apprehension about AML and novel drug targets. The combination of advanced genetic techniques, risk stratification, ongoing improvements, and innovations in treatment strategy will undoubtedly lead to improved survival outcomes in AML.

Primary Hemophagocytic Lymphohistiocytosis With Prolonged Primary Neurologic Presentation.

Primary hemophagocytic lympho-histiocytosis (HLH) is a hyperinflammatory syndrome with devastating consequences. Multisystem involvement is a hallmark of HLH; however, HLH may rarely present with signs and symptoms isolated to the central nervous system (CNS). Within the brain, HLH can mimic demyelination, chronic infection, or vasculitis, leading to a diagnostic delay of months to years. We describe here a 7-year-old boy who presented with a history of prolonged fever and multiple focal neurologic deficits, which were being treated as CNS tuberculosis at the referring hospital. In view of the relapsing course with multiple areas of hemorrhagic tumefactive lesions on neuroimaging, the diagnosis was revised to acquired demyelination, and he received multiple cycles of immunotherapy. A brain biopsy was inconclusive. Subsequently, 13 months after disease onset, the child presented with features of systemic HLH in the form of fever, pancytopenia, splenomegaly, elevated ferritin, and triglycerides. Primary HLH was suspected, and genetic testing revealed a likely pathologic compound heterozygous variation in the PRF1 gene confirming the diagnosis. We planned a hematopoietic stem cell transplant as definitive therapy, but the child succumbed to an episode of sepsis and aspiration pneumonia. We infer from this case that primary HLH is a great mimicker. A high index of suspicion is required to establish a timely diagnosis. Primary HLH may stay isolated to CNS for months and should be considered in the differential diagnosis of all refractory cases of demyelination.

Efficacy and safety of vemurafenib in Langerhans cell histiocytosis (LCH): A systematic review and meta-analysis.

Almost half of the patients with Langerhans cell histiocytosis (LCH) are refractory to primary induction chemotherapy or undergo reactivation. The ideal treatment modality for refractory/relapsed LCH is yet not evidenced. This review aimed to determine the efficacy and safety of vemurafenib (a BRAF pathway inhibitor) in LCH, particularly the refractory/relapsed cases. The literature search was conducted using PubMed, Embase, CENTRAL, and abstracts published in the SIOP meetings. Studies that described the outcome of patients of LCH being treated with vemurafenib, alone or in combination, were included. A total of 416 studies were screened, and after applying exclusion criteria, 22 studies (n = 107) were included in the final analysis. The first-line therapy was prednisolone plus vinblastine for most patients (n = 92, 86%), and vemurafenib was started upfront in 3 patients (3%). The median time to first clinical response with vemurafenib was one week. The median time to best response was 5.25 months. Out of 107 patients, 62 patients (58%) had ultimately no active disease (NAD) while 39 (36%) had active disease better (ADB), making the overall response rate (ORR) of 101/107, ie, 94.4% (CI 0.88; 0.98). The main adverse effects of vemurafenib were rash or photosensitivity (47%) and other cutaneous adverse events (15%). Vemurafenib is highly efficacious and safe in the treatment of refractory LCH; however, the timing of its commencement and duration of therapy is yet to be established. Larger prospective collaborative trials are needed to answer the appropriate treatment duration and effective maintenance therapy approach.

Molecular evaluation of gene mutation profiles and copy number variations in pediatric acute myeloid leukemia.

BACKGROUND: The objectives of this study were to investigate the mutation profiles of targeted genes and copy number variations (CNVs) in normal cytogenetics (CN) pediatric acute myeloid leukemia (AML). METHODS: This prospective study was conducted from October 2018 to December 2020. The next-generation sequencing (NGS) and chromosomal microarray analyses (CMA) were performed in pediatric CN-AML patients. RESULTS: Out of 94 children (aged ≤18 years), 70 patients with AML (24 excluded) underwent conventional karyotyping/cytogenetic analyses. Forty-five (64.3%) of patients had abnormal/ recurrent cytogenetic abnormalities and 25 (35.7%) had normal cytogenetics. Twenty-three out of 25 CN-AML were further processed for gene mutation profile and CNVs using NGS and CMA, respectively. Twenty-two out of 23 (95.7%) patients were detected to have mutations in various genes. The common mutations were: NRAS, NPM1, CEBPA, KRAS, KIT, RUNX1, NOTCH1, WT1, GATA1, GATA2, FLT3, KMT2D, FLT3-TKD, and PHF6. Copy number variations (CNVs) were detected in nine patients (39%), and eight (34.8%) had a long contiguous stretch of homozygosity (LCSH) /loss of heterozygosity (LOH). An LCSH was detected on chromosomes 5, 7, 11, and 19. The gains were more common than losses (8 vs 2). The gains were observed on chromosomes 8, 9, 14, 19, 21, and 22, and the losses were detected on chromosomes 7 and 10. Monosomy was observed in three patients. Three patients (monosomy7, n = 2, and FLT-ITD, n = 1) were reclassified into the high-risk category. Post-induction, complete remission was achieved in all evaluable patients. CONCLUSION: CN-AML patients have genetic abnormalities that can be detected by more advanced techniques like NGS and CMA. These genetic abnormalities play a role in risk stratification that may remain hidden in otherwise CN-AML.

Role of 18-Fluorodeoxyglucose Positron Emission Tomography-Computed Tomography in Predicting Residual Disease Posttreatment Completion in Retinoblastoma Patients.

Background: Retinoblastoma (RB) is the most common primary intraocular malignancy of childhood. Magnetic resonance imaging (MRI) of the orbit and brain is the preferred imaging modality to diagnose and define extent of disease as well as to assess response to therapy. Sometimes, it may be difficult to differentiate the presence of active residual disease from therapy-related changes based on posttreatment completion MRI. Materials and Methods: RB patients who completed treatment between January 2017 and October 2019 were retrospectively analyzed. We evaluated the utility of F-18-fluorodeoxyglucose (FDG) positron emission tomography-computed tomography (PET-CT) to predict active disease in RB patients who continued to have residual disease on MRI at completion of treatment. Results: Out of the 89 patients who completed treatment, dilemma regarding remission status was present in 11 children. All 11 patients underwent FDG-PET-CT. None of them had evidence of metabolically active disease in the orbit, optic nerve, brain, or rest of the body. After a median follow-up of 24 months, no children developed any evidence of disease progression in the form of local or distant relapse. Conclusion: Our results showed that in MRI doubtful cases, a nonavid FDG-PET is reassuring in avoiding further therapy as long as close follow-up can be ensured. FDG-PET-CT may emerge as a useful functional modality to predict disease activity in RB.

Neurocognitive outcomes in survivors of childhood acute lymphoblastic leukemia: Experience from a tertiary care center in India.

BACKGROUND: Data of neurocognitive deficits in survivors of acute lymphoblastic leukemia (ALL) is scarce from low middle-income countries (LMICs), and is influenced by biological and cultural variations. The objective of this study was to assess the prevalence and spectrum of neurocognitive deficits in a cohort of survivors from India. PROCEDURE: Seventy survivors of childhood ALL were evaluated for neurocognitive deficits by the Indian adaptation of Wechsler Intelligence Scale for Children - Fourth Edition (WISC-IVINDIA ). The prevalence of neurocognitive deficits was calculated based on the full-scale intelligence quotient (FSIQ), and scores in discrete domains like verbal comprehension, perceptual reasoning, working memory, and processing speed were calculated and compared to demographics, treatment, and sociocultural factors. RESULTS: The mean (SD) current age and time since diagnosis was 10.5 (±3.2) years and 5 (±2.8) years, respectively. The mean FSIQ was 86.1 ± 20.5, with significant neurocognitive deficit (FSIQ <90) being prevalent in 50% (95% CI: 38%-62%) of the cohort. The proportion of survivors with deficits in individual domains of verbal comprehension, perceptual reasoning, working memory, and processing speed were 49%, 50%, 47%, and 44%, respectively. The odds of having neurocognitive deficits were higher when a child belonged to lower socioeconomic strata (OR 5.7, p = .004), parents with lower education attainment (OR 4.3, p = .041), and whose birth order was higher (OR 20.1, p = .005). Age at diagnosis/assessment, chemotherapy received, or dose of radiotherapy did not have a direct impact on neurocognition. CONCLUSIONS AND RELEVANCE: Rates of neurocognitive deficits are higher in survivors in LMICs, with socioeconomic variables contributing more than the direct neurotoxic effects of treatment.

A Pilot Randomised Controlled Trial Examining the Benefit of a Neutropenic Diet for Children Undergoing Cancer Treatment.

Neutropenic diet(ND) has been hypothesized to decrease the rate of febrile neutropenia(FN) occurring post-chemotherapy for pediatric cancers. Despite widespread use, it has not shown to be of benefit by randomized controlled trials(RCT) in western countries. No RCT has been conducted in India/LMIC to evaluate its efficacy against the standard Indian diet. Forty-two(42) children, aged 3-14 y, with cancer, scheduled to receive strongly myelosuppressive chemotherapy were randomized to receive either neutropenic diet(n = 21) or standard Indian diet(n = 21) for one chemotherapeutic cycle. FN rate was recorded as the primary outcome while the focus of infection, antibiotic length, the requirement for hospital admission, adherence to diet were the secondary outcomes. The groups were similar in baseline characteristics. Twelve patients (57%) in the neutropenic diet and nine patients(43%) in the standard diet arm developed FN. Patients in ND-arm had significantly higher chance of getting neutropenic enterocolitis(NEC) (33.33% vs 4.76% p = 0.044). Mortality (14.29%vs 0%, p = 0.23) and requirement for admission (47.6%vs 19.05%, p = 0.06), was more in the ND-arm but statistically non-significant. There was no significant difference in antibiotic length. Adherence was similar in both groups (95% vs 98%). Neutropenic diet was not effective in reducing FN rate and was associated with higher rate of NEC when compared to the standard diet.

The effect of placebo in split-scalp and whole-head platelet-rich plasma trials for androgenetic alopecia differs: Findings from a systematic review with quantitative evidence syntheses.

BACKGROUND: Some studies have shown that platelet-rich plasma (PRP) improves androgenetic alopecia (AGA), while others do not. We determined whether the placebo effect significantly varies between split-scalp and whole-head trials on PRP monotherapy for AGA. Our rationale was based on the plausibility of PRP diffusing to the control (i.e., "placebo") side of split-scalp trials. This is not possible in whole-head studies. METHODS: We systematically searched the literature for available data. Our choice of analyses and outcomes were determined by the available data. RESULTS: Our endpoint was change in total hair density 6 months after baseline. Our regression showed that total hair density after 6 months was significantly (p < 0.05) higher in the placebo arm of split-scalp trials, compared to whole-head studies, by 37 hairs/cm2 . Our one-arm meta-analyses showed that the pooled change in total hair density between the PRP side and placebo side in split-scalp studies was -3 hairs/cm2 (p = 0.37), that is, a slight decrease in hair density in the placebo side of the scalp. For whole-head studies, the corresponding difference in total hair density between patients receiving PRP and those on placebo was -30 hairs/cm2 (p = 0.000017), that is, a much larger decrease in hair density. Patients in the placebo group in whole-head trials lost significantly more hair than in the placebo side of the split-head trials where hair loss was comparatively reduced - presumably because of PRP diffusing from the treatment side of the scalp. CONCLUSIONS: The association between design (i.e., split-scalp vs. whole-head) and outcome, in placebo arms of AGA trials on PRP monotherapy, had never been reported. This "design effect" could partly reconcile the incongruent conclusions across the PRP literature for AGA; furthermore, clinical guidelines can consider "design effect" when selecting evidence to base care practices on.