CC BY-NC-ND 4.0 · Ann Natl Acad Med Sci 2021; 57(02): 120-122
DOI: 10.1055/s-0041-1728971

Loss to Follow-up: A Deceptive Enigma

Sandeep Patel
1   Department of Orthopedics, Post Graduate Institute of Medical Education & Research, Chandigarh, Punjab, India
Vishal Kumar
1   Department of Orthopedics, Post Graduate Institute of Medical Education & Research, Chandigarh, Punjab, India
Shahnawaz Khan
1   Department of Orthopedics, Post Graduate Institute of Medical Education & Research, Chandigarh, Punjab, India
Amit Salaria
1   Department of Orthopedics, Post Graduate Institute of Medical Education & Research, Chandigarh, Punjab, India
› Author Affiliations


Loss to follow-up indicates both patients not reporting and inability to trace them during the required follow-up period or study period. Significant loss to follow-up can affect the validity of a study and thereby the impact of that study. The importance of loss to follow-up has been very scarcely and meagerly highlighted in literature. More than one-fifth loss to follow-up can lead to significant selection bias. Loss to follow-up affects delivery of appropriate patient care. In the cohort studies, follow-up rates of 50 to 80% are accepted by authors, due to lack of any recommendations. The causes of loss to follow-up may vary from patient’s age, occupation, chronicity of the disease, etc. Loss to follow-up needs to be reported in all prospective studies, and intention to treat analysis should be applied. This will improve the validity of study, provide reliable results, and reflect the true effect of the intervention used in the study. It also helps to determine the actual survival rates in fatal diseases. The course of a disease can also be monitored, and appropriate intervention can be done at an appropriate point of time to prevent morbidity and mortality. Its overall benefits are better patient care and improved outcomes of the treatment method.

Publication History

Article published online:
10 May 2021

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  • References

  • 1 Small WP. Lost to follow-up. Lancet 1967; 1 (7497) 997-999
  • 2 Dettori JR. Loss to follow-up. Evid Based Spine Care J 2011; 2 (01) 7-10
  • 3 Kristman V, Manno M, Côté P. Loss to follow-up in cohort studies: how much is too much?. Eur J Epidemiol 2004; 19 (08) 751-760
  • 4 Fewtrell MS, Kennedy K, Singhal A. et al. How much loss to follow-up is acceptable in long-term randomised trials and prospective studies?. Arch Dis Child 2008; 93 (06) 458-461
  • 5 Little RJA, Rubin DB. Statistical Analysis with Missing Data. New York: John Wiley & Sons 1987
  • 6 Akl EA, Briel M, You JJ. et al. Potential impact on estimated treatment effects of information lost to follow-up in randomised controlled trials (LOST-IT): systematic review. BMJ 2012; 344: e2809
  • 7 Swaminathan R, Rama R, Shanta V. Lack of active follow-up of cancer patients in Chennai, India: implications for population-based survival estimates. Bull World Health Organ 2008; 86 (07) 509-515
  • 8 Murray DW, Britton AR, Bulstrode CJK. Loss to follow-up matters. J Bone Joint Surg Br 1997; 79 (02) 254-257
  • 9 Baron G, Boutron I, Giraudeau B, Ravaud P. Violation of the intent-to-treat principle and rate of missing data in superiority trials assessing structural outcomes in rheumatic diseases. Arthritis Rheum 2005; 52 (06) 1858-1865
  • 10 Somerson JS, Bartush KC, Shroff JB, Bhandari M, Zelle BA. Loss to follow-up in orthopaedic clinical trials: a systematic review. Int Orthop 2016; 40 (11) 2213-2219
  • 11 Zelle BA, Buttacavoli FA, Shroff JB, Stirton JB. Loss of follow-up in orthopaedic trauma: who is getting lost to follow-up?. J Orthop Trauma 2015; 29 (11) 510-515
  • 12 Solberg TK, Sørlie A, Sjaavik K, Nygaard ØP, Ingebrigtsen T. Would loss to follow-up bias the outcome evaluation of patients operated for degenerative disorders of the lumbar spine?. Acta Orthop 2011; 82 (01) 56-63
  • 13 Zunzunegui MV, Béland F, Gutiérrez-Cuadra P. Loss to follow-up in a longitudinal study on aging in Spain. J Clin Epidemiol 2001; 54 (05) 501-510
  • 14 Sprague S, Leece P, Bhandari M, Tornetta PIII, Schemitsch E, Swiontkowski MF. S.P.R.I.N.T. Investigators. Limiting loss to follow-up in a multicenter randomized trial in orthopedic surgery. Control Clin Trials 2003; 24 (06) 719-725
  • 15 Mehta KG, Baxi R, Patel S, Parmar M. Drug adherence rate and loss to follow-up among people living with HIV/AIDS attending an ART centre in a tertiary government hospital in western India. J Family Med Prim Care 2016; 5 (02) 266-269