Enhancing the h index for the objective assessment of healthcare researcher performance and impact.
OBJECTIVE
To investigate whether the h index (a bibliometric tool which is increasingly used to assess and appraise an individual's research performance) could be improved to better measure the academic performance and citation profile for individual healthcare researchers.


METHODS
Cohort study.


METHODS
Faculty of Medicine, Imperial College London, UK.


METHODS
Publication lists from 1 January 2000 until 31 December 2009 for 501 academic healthcare researchers from the Faculty of Medicine.


METHODS
The h index for each researcher was calculated over a nine-year period. The citation count for each researcher was differentiated into high (h(2) upper), core (h(2) centre) and low (h(2) lower) visibility areas. Segmented regression model (sRM) was used to statistically estimate number of high visibility publications (sRM value). Validity of the h index and other proposed adjuncts were analysed against academic rank and conventional bibliometric indicators.


RESULTS
Construct validity was demonstrated for h index, h(2) upper, h(2) centre, h(2) lower and sRM value (all P < 0.05). Convergent validity of the h index and sRM value was shown by significant correlations with total number of publications (r = 0.89 and 0.86 respectively, P < 0.05) and total number of citations (r = 0.96 and 0.65, respectively, P < 0.05). Significant differences in h index and sRM value existed between non-physician and physician researchers (P < 0.05).


CONCLUSIONS
This study supports the construct validity of the h index as a measure of healthcare researcher academic rank. It also identifies the assessment value of our developed indices of h(2) upper, h(2) centre, h(2) lower and sRM. These can be applied in combination with the h index to provide additional objective evidence to appraise the performance and impact of an academic healthcare researcher.
Department of Surgery and Cancer, Imperial College London, St Mary's Hospital, London W2 1NY,  UK.
Vanash M
VM
Patel
Hutan
H
Ashrafian
Lutz
L
Bornmann
Rüdiger
R
Mutz
Jonathan
J
Makanjuola
Petros
P
Skapinakis
Ara
A
Darzi
Thanos
T
Athanasiou
D015706:Bibliometrics; D015331:Cohort Studies; D006302:Health Services Research; D006801:Humans; D008131:London; D011642:Publications; D011643:Publishing; D012108:Research Personnel