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Table 1 VOC frequency studies

From: A systematic literature review of frequency of vaso-occlusive crises in sickle cell disease

Study identifier Country N Mean age VOC definition # of reported VOCs/year
Mean SD Range IQR
Le et al. [16] Belgium 139 21a Hospitalization 0/100 PYa,b
      29.6/100 PYa,c    
Donaldson et al. [22] Jamaica 50 18.5 NR 5.63/100 PYd
Upadhye et al. [23] India 75 NR NR 9.7/100 PY
Lamarre et al. [24] French West Indies 49 11.9 Hospitalization 0.26e 0.39
   44 11.4   0.41f    
Willen et al. [25] Multiple 165 10 Hospitalization 0.27a
Asnani et al. [26] Jamaica 8504 NR Healthcare visit (OP or IP) to center; recorded in database 0.4 0.7
DeBaun et al. [27] U.S 159 9a Hospitalization and treatment with opioids 0.46a
Boyd et al. [28] U.S 242 0.25 Healthcare visit (OP or IP) to clinic 0.47g
Rezende et al. [29] Brazil 461 9.2 Healthcare visit (OP or IP) to center 51/100 PY 48.9–53.4
Schuchard et al. [30] U.S 35 0.6 Healthcare visit (OP or IP) to center 0.15h
   13 1.6   0.9i    
   17 3.0   0.52j    
Ceglie et al. [31] Italy 16 10.5 Hospitalization at study center 0.6k
   23 10.3   1.6l    
Inati et al. [32] Lebanon 335 8.6 Hospitalization 0.6 0.6 0.04–2.4
Jain et al. [33] India 833 NR Healthcare visit (OP or IP) to center 64/100 PY
Lettre et al. [34] Multiple 1275 14.5 NR 0.7/PY 1.4
Nimgaonkar et al. [35] India 137 14a NR 0.7
Barner et al. [36] U.S 1190 NR Healthcare visit (OP, IP, or ED) 4.1/5 year study period 5
Willen et al. [37] U.S 197 11 Hospitalization and treatment with opioids 0.86
Yates et al. [38] Multiple 15 9.6a Hospitalization 1.18a,m 0–1.94
Joseph et al. [39] U.S 16,092 36.7 Healthcare visit (OP, IP, or ED); Texas Medicaid claims 1.2
Leleu et al. [40] France 157 33a Healthcare visit (OP, IP, or ED); French National Health Data System 1.9n
Janecek et al. [41] U.S 66 38.8 Healthcare visit (OP, IP, or ED) 2o
Dave et al. [42] India 404 19 Healthcare visit (OP or IP) to care system 2.77
Madu et al. [43] Nigeria 126 24.9 Healthcare visit (OP or IP) to center 3 4.8
Osunkwo et al. [18] Multiple 2145 NR Self-reported (patient survey; hospitalization, ED, managed at home) 3a 2–6
Latremouille-Viau et al. [44] U.S 18,287 28.5 Healthcare visit (OP, IP, or ED); Medicaid and Medicare claims 3.1p  
   15,431 48.2   3.4q    
Shah et al. [45] U.S 8521 32.9 Healthcare visit (OP, IP, or ED); Medicaid claims 3.31
Desai et al. [46] U.S 44,033 15.7 Healthcare visit (≥ 2 OP, or ≥ 1 IP, or ED); Medicaid claims 3.71
James et al. [19] Multiple 1513 24.1 Self-reported (patient survey; hospitalization, ED, managed at home) 5.2
Alsultan et al. [47] Saudi Arabia 159 17.8 Hospitalization for > 48 h 5.6 5.7 0–36
Andemariam et al. [20] U.S 384 30.1 Self-reported (patient survey; hospitalization, ED, managed at home) 7.1 5.7
Bronte-Hall et al. [48] U.S 149 33.2a Healthcare visit (OP or IP) to center 10.4
McClish et al. [21] U.S 87 33.6 Self-reported (patient diary) 6.0/6 monthsk
   139 34.5   6.8/6 monthsl    
Shome et al. [17] Bahrain 51 29.6 Healthcare visit (OP or IP) to center 18.2m 17.5
  1. ED emergency department, IP inpatient, IQR interquartile range, NR not reported, OP outpatient, PY patient-year, SCD sickle cell disease, SD standard deviation, VOC vaso-occlusive crisis
  2. aMedian reported
  3. bAdults study arm
  4. cAdolescents study arm
  5. dCases arm, patients with steady-state HBF levels below 1%
  6. eHbSC study arm
  7. fHbSS study arm
  8. gNon-asthmatic study arm
  9. hPatients who started hydroxyurea between 5 months and 1 year of age
  10. iPatients who started hydroxyurea between 1 and 2 years of age
  11. jPatients who started hydroxyurea between 2 and 5 years of age
  12. kMale study arm
  13. lFemale study arm
  14. mPre-hydroxyurea therapy study arm
  15. nPatients who had at least 2 inpatient stays for SCD diagnosis/chronic long-term SCD, or a reimbursement for Siklos/Hydrea
  16. oPre-assessment study arm
  17. pMedicaid claims study arm
  18. qMedicare claims study arm