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Dr Ariyapala Samaranayaka

PositionSenior Research Fellow
QualificationsBSc MPhil PhD
Research summaryBiostatistics

Research

As a member of the Biostatistics Centre, Ari is available for biostatistical advice to researchers in the Division of Health Sciences, University of Otago. He has experience as a biostatistician in health researches more than a decade, and has contributed to more than 50 peer-reviewed health-related publications. He has worked on a wide variety of projects involving injuries, motor vehicle traffic crashes, farm and work injuries, disabilities, large longitudinal cohort studies, cross sectional surveys, as well as on related methodological developments.

Publications

Richardson, A. E., Derrett, S., Samaranayaka, A., & Wyeth, E. H. (2021). Prevalence and predictors of psychological distress following injury: Findings from a prospective cohort study. Injury Epidemiology, 8(1), 41. doi: 10.1186/s40621-021-00337-7

Shettigar, R., Samaranayaka, A., Schollum, J. B. W., Wyeth, E. H., Derrett, S., & Walker, R. J. (2021). Predictors of health deterioration among older New Zealanders undergoing dialysis: A three-year accelerated longitudinal cohort study. Canadian Journal of Kidney Health & Disease, 8. doi: 10.1177/20543581211022207

Derrett, S., Wyeth, E. H., Richardson, A., Davie, G., Samaranayaka, A., Lilley, R., & Harcombe, H. (2021). Prospective Outcomes of Injury Study 10 Years on (POIS-10): An observational cohort study. Methods & Protocols, 4(2), 35. doi: 10.3390/mps4020035

Samaranayaka, A., Cameron, C., & Turner, R. M. (2021). Sample size in health research. New Zealand Medical Student Journal, 32, 52-54. Retrieved from https://www.nzmsj.com/

Connor, J., Brookland, R., & Samaranayaka, A. (2021). Older drivers and their future mobility: Views and involvement of their adult children. Journal of Applied Gerontology, 40(1), 55-66. doi: 10.1177/0733464819894545

Connor, J., Brookland, R., & Samaranayaka, A. (2021). Older drivers and their future mobility: Views and involvement of their adult children. Journal of Applied Gerontology, 40(1), 55-66. doi: 10.1177/0733464819894545

Journal - Research Article

Richardson, A. E., Derrett, S., Samaranayaka, A., & Wyeth, E. H. (2021). Prevalence and predictors of psychological distress following injury: Findings from a prospective cohort study. Injury Epidemiology, 8(1), 41. doi: 10.1186/s40621-021-00337-7

Journal - Research Article

Richardson, A., Samaranayaka, A., Sullivan, M., & Derrett, S. (2021). Secondary health conditions and disability among people with spinal cord injury: A prospective cohort study. Journal of Spinal Cord Medicine, 44(1), 19-28. doi: 10.1080/10790268.2019.1581392

Journal - Research Article

Samaranayaka, A., Cameron, C., & Turner, R. M. (2021). Sample size in health research. New Zealand Medical Student Journal, 32, 52-54. Retrieved from https://www.nzmsj.com/

Journal - Research Article

Shettigar, R., Samaranayaka, A., Schollum, J. B. W., Wyeth, E. H., Derrett, S., & Walker, R. J. (2021). Predictors of health deterioration among older New Zealanders undergoing dialysis: A three-year accelerated longitudinal cohort study. Canadian Journal of Kidney Health & Disease, 8. doi: 10.1177/20543581211022207

Journal - Research Article

Cameron, C., Samaranayaka, A., & Turner, R. M. (2020). P values: What are their significance? New Zealand Medical Student Journal, 31, 48-49.

Journal - Research Article

Harcombe, H., Samaranayaka, A., Wyeth, E. H., Davie, G., Cameron, I. D., Lilley, R., & Derrett, S. (2020). Predictors of subsequent injury at work: Findings from a prospective cohort of injured workers in New Zealand. Occupational & Environmental Medicine. Advance online publication. doi: 10.1136/oemed-2020-106597

Journal - Research Article

Richardson, A., Gurung, G., Samaranayaka, A., Gardner, D., de Graaf, B., Wyeth, E. H., Derrett, S., … McBride, D. (2020). Risk and protective factors for post-traumatic stress among New Zealand military personnel: A cross sectional study. PLoS ONE, 15(4), e0231460. doi: 10.1371/journal.pone.0231460

Journal - Research Article

Sopoaga, F., Nada-Raja, S., Leckie, T., & Samaranayaka, A. (2020). Mental health and wellbeing of Pacific students: Protocol of a Pacific perspective study. Pacific Health Dialog, 21(5), 272-280. doi: 10.26635/phd.2020.626

Journal - Research Article

Turner, R., Samaranayaka, A., & Cameron, C. (2020). Parametric vs nonparametric statistical methods: Which is better, and why? New Zealand Medical Student Journal, 30, 61-62.

Journal - Research Article

Baker, W., Samaranayaka, A., Wyeth, E., Ameratunga, S., & Derrett, S. (2019). Migrants and disability following injury: Findings from a prospective study in New Zealand. Australian & New Zealand Journal of Public Health, 43(5), 470-476. doi: 10.1111/1753-6405.12927

Journal - Research Article

Chan, J. E., Samaranayaka, A., & Paterson, H. (2019). Seasonal and gestational variation in perinatal depression in a prospective cohort in New Zealand. Australian & New Zealand Journal of Obstetrics & Gynaecology, 59, 514-522. doi: 10.1111/ajo.12912

Journal - Research Article

Cryer, C., Davie, G., Gulliver, P., & Samaranayaka, A. (2019). Use of mixed methods to investigate case definitions to improve the identification of serious injury cases from hospital episode data. Injury Prevention, 25(6), 552-556. doi: 10.1136/injuryprev-2019-043293

Journal - Research Article

Derrett, S., Gunter, K. E., Samaranayaka, A., Singer, S. J., Nocon, R. S., Quinn, M. T., … Chin, M. H. (2019). Development and testing of the Provider and Staff Perceptions of Integrated Care (PSPIC) survey. Medical Care Research & Review, 76(6), 807-829. doi: 10.1177/1077558717745936

Journal - Research Article

McNoe, B., Schollum, J. B. W., Derrett, S., Marshall, M. R., Henderson, A., Samaranayaka, A., & Walker, R. J. (2019). Recruitment and participant baseline characteristics in the dialysis outcomes in those aged 65 years or older study. BMC Nephrology, 20, 137. doi: 10.1186/s12882-019-1328-8

Journal - Research Article

Samaranayaka, A., Turner, R., & Cameron, C. (2019). Kaplan-Meier plots. New Zealand Medical Student Journal, 28, 45-46.

Journal - Research Article

Turner, R. M., Cameron, C., & Samaranayaka, A. (2019). Understanding receiver operator characteristic (ROC) curves. New Zealand Medical Student Journal, 29, 50-51.

Journal - Research Article

Wyeth, E. H., Samaranayaka, A., Lambert, M., Tapsell, M., Anselm, D., Ellison, P., … Derrett, S. (2019). Understanding longer-term disability outcomes for Māori and non-Māori after hospitalisation for injury: Results from a longitudinal cohort study. Public Health, 176, 118-127. doi: 10.1016/j.puhe.2018.08.014

Journal - Research Article

Wyeth, E., Lambert, M., Samaranayaka, A., Harcombe, H., Davie, G., & Derrett, S. (2019). Subsequent injuries experienced by Māori: Results from a 24-month prospective study in New Zealand. New Zealand Medical Journal, 132(1499), 23-35. Retrieved from https://www.nzma.org.nz/journal

Journal - Research Article

Davie, G., Samaranayaka, A., & Derrett, S. (2018). The role of pre-existing comorbidity on the rate of recovery following injury: A longitudinal cohort study. PLoS ONE, 13(2), e0193019. doi: 10.1371/journal.pone.0193019

Journal - Research Article

De Silva, R. K., Siriwardena, B. S. M. S., Samaranayaka, A., Abeyasinghe, W. A. M. U. L., & Tilakaratne, W. M. (2018). A model to predict nodal metastasis in patients with oral squamous cell carcinoma. PLoS ONE, 13(8), e0201755. doi: 10.1371/journal.pone.0201755

Journal - Research Article

Harcombe, H., Davie, G., Wyeth, E., Samaranayaka, A., & Derrett, S. (2018). Injury upon injury: A prospective cohort study examining subsequent injury claims in the 24 months following a substantial injury. Injury Prevention, 24(6), 460-467. doi: 10.1136/injuryprev-2017-042467

Journal - Research Article

Leitch, S., Dovey, S. M., Samaranayaka, A., Reith, D. M., Wallis, K. A., Eggleton, K. S., … Williamson, M. I., … Tilyard, M. W. (2018). Characteristics of a stratified random sample of New Zealand general practices. Journal of Primary Health Care, 10(2), 114-124. doi: 10.1071/HC17089

Journal - Research Article

Samaranayaka, S., Walker, R. J., Samaranayaka, A., Derrett, S., & Schollum, J. B. W. (2018). Medication exposure and health outcomes in older patients with end-stage kidney disease: A prospective study undertaken in New Zealand. Drugs & Aging, 35, 1005-1015. doi: 10.1007/s40266-018-0582-y

Journal - Research Article

Taylor, J. E., Connolly, M. J., Brookland, R., & Samaranayaka, A. (2018). Understanding driving anxiety in older adults. Maturitas, 118, 51-55. doi: 10.1016/j.maturitas.2018.10.008

Journal - Research Article

Windner, Z., Crengle, S., de Graaf, B., Samaranayaka, A., & Derrett, S. (2018). New Zealanders' experiences and pathways to a diagnosis of bowel cancer: A cross-sectional descriptive study of a younger cohort. New Zealand Medical Journal, 131(1483), 30-39. Retrieved from https://www.nzma.org.nz/journal

Journal - Research Article

Derrett, S., Samaranayaka, A., Schollum, J. B. W., McNoe, B., Marshall, M. R., Williams, S., Wyeth, E. H., & Walker, R. J. (2017). Predictors of health deterioration among older adults after 12 months of dialysis therapy: A longitudinal cohort study from New Zealand. American Journal of Kidney Diseases, 70(6), 798-806. doi: 10.1053/j.ajkd.2017.06.023

Journal - Research Article

Hoye, N. A., Wilson, L. C., Wilkins, G. T., Jardine, D. L., Putt, T. L., Samaranayaka, A., Schollum, J. B. W., & Walker, R. J. (2017). Endovascular renal denervation in end-stage kidney disease patients: Cardiovascular protection: A proof-of-concept study. Kidney International Reports, 2(5), 856-865. doi: 10.1016/j.ekir.2017.04.012

Journal - Research Article

Page, M. J., Wyeth, E. H., Samaranayaka, A., McNoe, B., Walker, R. C., Schollum, J., … Walker, R., & Derrett, S. (2017). Accuracy of ethnicity data recorded in hospital-based patient clinical records and the Australia and New Zealand Dialysis and Transplant Registry. New Zealand Medical Journal, 130(1454), 65-71. Retrieved from https://www.nzma.org.nz/journal

Journal - Research Article

Samaranayaka, C., Samaranayaka, A., Barson, D., & De Silva, R. K. (2017). Factors influencing trends in trauma-associated orbital cavity reconstruction procedures and time delay: New Zealand national data 2000–2014. Trauma, 20(4), 258-267. doi: 10.1177/1460408617719477

Journal - Research Article

Wyeth, E. H., Samaranayaka, A., Davie, G., & Derrett, S. (2017). Prevalence and predictors of disability for Māori 24 months after injury. Australian & New Zealand Journal of Public Health, 41(3), 262-268. doi: 10.1111/1753-6405.12657

Journal - Research Article

Harcombe, H., Samaranayaka, A., & Derrett, S. (2016). Predictors of reduced frequency of physical activity 3 months after injury: Findings from the prospective outcomes of injury study. Physical Therapy, 96(12), 1885-1895. doi: 10.2522/ptj.20160038

Journal - Research Article

Nixon, G., Samaranayaka, A., de Graaf, B., McKechnie, R., Rodwell, P., & Blattner, K. (2015). The impact of a rural scanner in overcoming urban versus rural disparities in the utilisation of computed tomography. Australian Journal of Rural Health, 23, 150-154. doi: 10.1111/ajr.12125

Journal - Research Article

Slatter, T. L., Hsia, H., Samaranayaka, A., Sykes, P., Clow, W., Devenish, C. J., … Royds, J. A., … Hung, N. A. (2015). Loss of ATRX and DAXX expression identifies poor prognosis for smooth muscle tumours of uncertain malignant potential and early stage uterine leiomyosarcoma. Journal of Pathology: Clinical Research, 1(2), 95-105. doi: 10.1002/cjp2.11

Journal - Research Article

Connor, J., Cousins, K., Samaranayaka, A., & Kypri, K. (2014). Situational and contextual factors that increase the risk of harm when students drink: Case-control and case-crossover investigation. Drug & Alcohol Review, 33(4), 401-411. doi: 10.1111/dar.12172

Journal - Research Article

Cryer, C., Langley, J. D., Samaranayaka, A., Davie, G., Morgaine, K., Lilley, R., & Barson, D. (2014). An outcome evaluation of a New Zealand farm safety intervention: A historical cohort study. American Journal of Industrial Medicine, 57(4), 458-467. doi: 10.1002/ajim.22290

Journal - Research Article

Cryer, C., Samaranayaka, A., Langley, J. D., & Davie, G. (2014). The epidemiology of life-threatening work-related injury: A demonstration paper. American Journal of Industrial Medicine, 57(4), 425-437. doi: 10.1002/ajim.22301

Journal - Research Article

Harcombe, H., Derrett, S., Samaranayaka, A., Davie, G., Wyeth, E., & Wilson, S. (2014). Factors predictive of subsequent injury in a longitudinal cohort study. Injury Prevention, 20(6), 393-400. doi: 10.1136/injuryprev-2014-041183

Journal - Research Article

Langley, J. D., Lilley, R., Wilson, S., Derrett, S., Samaranayaka, A., Davie, G., … Wyeth, E. H., Hansen, P., & Hokowhitu, B. (2014). Factors associated with non-participation in one or two follow-up phases in a cohort study of injured adults. Injury Prevention, 19, 428-433. doi: 10.1136/injuryprev-2012-040685

Journal - Research Article

Langley, J., Lilley, R., Samaranayaka, A., & Derrett, S. (2014). Work status and disability trajectories over 12 months after injury among workers in New Zealand. New Zealand Medical Journal, 127(1390). Retrieved from http://www.nzma.org.nz/journal

Journal - Research Article

Nixon, G., Samaranayaka, A., de Graaf, B., McKechnie, R., Blattner, K., & Dovey, S. (2014). Geographic disparities in the utilisation of computed tomography scanning services in southern New Zealand. Health Policy, 118(2), 222-228. doi: 10.1016/j.healthpol.2014.05.002

Journal - Research Article

Wilson, S. J., Derrett, S., Cameron, I. D., Samaranayaka, A., Davie, G., & Langley, J. (2014). Prevalence of poor outcomes soon after injury and their association with the severity of the injury. Injury Prevention, 20, 57-61. doi: 10.1136/injuryprev-2012-040690

Journal - Research Article

Chalmers, D. J., Samaranayaka, A., & McNoe, B. M. (2013). Risk factors for injury in community-level football: A cohort study. International Journal of Injury Control & Safety Promotion, 20(1), 68-78. doi: 10.1080/17457300.2012.674044

Journal - Research Article

Derrett, S., Wilson, S., Samaranayaka, A., Langley, J., Wyeth, E., Ameratunga, S., Lilley, R., Davie, G., & Mauiliu, M. (2013). Prevalence and predictors of disability 24-months after injury for hospitalised and non-hospitalised participants: Results from a longitudinal cohort study in New Zealand. PLoS ONE, 8(11), e80194. doi: 10.1371/journal.pone.0080194

Journal - Research Article

Langley, J., Begg, D., Samaranayaka, A., Brookland, R., & Weiss, H. (2013). Unsupervised driving by learner licence holders: Associated characteristics and crash risk. Accident Analysis & Prevention, 60, 24-30. doi: 10.1016/j.aap.2013.07.021

Journal - Research Article

Langley, J., Samaranayaka, A., & Begg, D. J. (2013). Age, period and cohort effects on the incidence of motorcyclist casualties in traffic crashes. Injury Prevention, 19(3), 153-157. doi: 10.1136/injuryprev-2012-040345

Journal - Research Article

Mauiliu, M., Derrett, S., Samaranayaka, A., Sopoaga, F., Kokaua, J., & Davie, G. (2013). Pacific peoples three months after injury: A comparison of outcomes between Pacific and non-Pacific participants in a NZ cohort study. Australian & New Zealand Journal of Public Health, 37(5), 463-469. doi: 10.1111/1753-6405.12124

Journal - Research Article

Wyeth, E. H., Derrett, S., Hokowhitu, B., & Samaranayaka, A. (2013). Indigenous injury outcomes: Life satisfaction among injured Māori in New Zealand three months after injury. Health & Quality of Life Outcomes, 11, 120. doi: 10.1186/1477-7525-11-120

Journal - Research Article

Begg, D., Sullman, M., & Samaranayaka, A. (2012). The characteristics of young pre-licensed drivers: Evidence from the New Zealand Drivers Study. Accident Analysis & Prevention, 45, 539-546. doi: 10.1016/j.aap.2011.09.006

Journal - Research Article

Chalmers, D. J., Samaranayaka, A., Gulliver, P., & McNoe, B. (2012). Risk factors for injury in rugby union football in New Zealand: A cohort study. British Journal of Sports Medicine, 46(2), 95-102. doi: 10.1136/bjsports-2011-090272

Journal - Research Article

Derrett, S., Samaranayaka, A., Wilson, S., Langley, J., Ameratunga, S., Cameron, I. D., Lilley, R., Wyeth, E., & Davie, G. (2012). Prevalence and predictors of sub-acute phase disability after injury among hospitalised and non-hospitalised groups: A longitudinal cohort study. PLoS ONE, 7(9), e44909. doi: 10.1371/journal.pone.0044909

Journal - Research Article

Langley, J., Begg, D., Brookland, R., Samaranayaka, A., Jordan, H., & Davie, G. (2012). Nonprogression through graduated driver licensing: Characteristics, traffic offending, and reasons for nonprogression. Traffic Injury Prevention, 13(1), 7-13. doi: 10.1080/15389588.2011.635170

Journal - Research Article

Wilson, S. J., Begg, D. J., & Samaranayaka, A. (2012). Validity of using linked hospital and police traffic crash records to analyse motorcycle injury crash characteristics. Accident Analysis & Prevention, 49, 30-35. doi: 10.1016/j.aap.2011.03.007

Journal - Research Article

Cryer, C., Gulliver, P., Langley, J., Davie, G., Samaranayaka, A., & Fowler, C. (2011). A proposed theoretical definition to address the undercounting of injury deaths. Injury Prevention, 17, 219-221. doi: 10.1136/injuryprev-2011-040039

Journal - Research Article

Davie, G., Samaranayaka, A., Langley, J. D., & Barson, D. (2011). Estimating person-based injury incidence: Accuracy of an algorithm to identify readmissions from hospital discharge data. Injury Prevention, 17(5), 338-342. doi: 10.1136/injuryprev-2011-040090

Journal - Research Article

Derrett, S., Davie, G., Ameratunga, S., Wyeth, E., Colhoun, S., Wilson, S., Samaranayaka, A., Lilley, R., Hokowhitu, B., Hansen, P., & Langley, J. (2011). Prospective Outcomes of Injury Study: Recruitment, and participant characteristics, health and disability status. Injury Prevention, 17(6), 415-418. doi: 10.1136/injuryprev-2011-040044

Journal - Research Article

Kypri, K., Samaranayaka, A., Connor, J., Langley, J. D., & MacLennan, B. (2011). Non-response bias in a web-based health behaviour survey of New Zealand tertiary students. Preventive Medicine, 53(4-5), 274-277. doi: 10.1016/j.ypmed.2011.07.017

Journal - Research Article

Langley, J., Samaranayaka, A., Davie, G., & Campbell, A. J. (2011). Age, cohort and period effects on hip fracture incidence: Analysis and predictions from New Zealand data 1974-2007. Osteoporosis International, 22(1), 105-111. doi: 10.1007/s00198-010-1205-6

Journal - Research Article

Samaranayaka, A., & Fletcher, D. (2010). Modelling environmental stochasticity in adult survival for a long-lived species. Ecological Modelling, 221(3), 423-427. doi: 10.1016/j.ecolmodel.2009.10.016

Journal - Research Article

Davie, G., Langley, J., Samaranayaka, A., & Weatherspoon, M. E. (2008). Accuracy of injury coding under ICD-10-AM for New Zealand public hospital discharges. Injury Prevention, 14, 319-323. doi: 10.1136/ip.2007.017954

Journal - Research Article

dos Santos Dias, C. T., Samaranayaka, A., & Manly, B. (2008). On the use of correlated beta random variables with animal population modelling. Ecological Modelling, 215, 293-300.

Journal - Research Article

Samaranayaka, A., Engås, A., & Jørgensen, T. (1997). Effects of hanging ratio and fishing depth on the catch rates of drifting tuna gillnets in Sri Lankan waters. Fisheries Research, 29, 1-12.

Journal - Research Article

Derrett, S., Wyeth, E. H., Richardson, A., Davie, G., Samaranayaka, A., Lilley, R., & Harcombe, H. (2021). Prospective Outcomes of Injury Study 10 Years on (POIS-10): An observational cohort study. Methods & Protocols, 4(2), 35. doi: 10.3390/mps4020035

Journal - Research Other

Derrett, S., Harcombe, H., Wyeth, E., Davie, G., Samaranayaka, A., Hansen, P., … Sullivan, T., Wilson, S., & Barson, D. (2017). Subsequent Injury Study (SInS): Improving outcomes for injured New Zealanders. Injury Prevention, 23(6), 429. doi: 10.1136/injuryprev-2016-042193

Journal - Research Other

Dovey, S. M., Leitch, S., Wallis, K. A., Eggleton, K. S., Cunningham, W. K., Williamson, M. I., … Tilyard, M. W., Reith, D. M., Samaranayaka, A., & Hall, J. E. (2017). Epidemiology of patient harms in New Zealand: Protocol of a general practice records review study. JMIR Research Protocols, 6(1), e10. doi: 10.2196/resprot.6696

Journal - Research Other

Tun, T., Nyunt, W. W., Latt, K. Z., Samaranayaka, A., Crump, J. A., Thinn, K. K., Cook, G. M., & Aung, H. L. (2016). Drug-resistant tuberculosis among previously treated patients in Yangon, Myanmar. International Journal of Mycobacteriology, 5(3), 366-367. doi: 10.1016/j.ijmyco.2016.06.004

Journal - Research Other

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