 |
| LETTER |
|
|
|
| Year : 2016 | Volume
: 62
| Issue : 1 | Page : 51-52 |
Calculating incidence in cross-sectional studies
SK Raina
Department of Community Medicine, Dr. Rajendra Prasad Government Medical College, Tanda, Himachal Pradesh, India
| Date of Web Publication | 5-Jan-2016 |
Correspondence Address:
S K Raina
Department of Community Medicine, Dr. Rajendra Prasad Government Medical College, Tanda, Himachal Pradesh
India
 Source of Support: None, Conflict of Interest: None  | Check |
DOI: 10.4103/0022-3859.173217
How to cite this article:
Raina S K. Calculating incidence in cross-sectional studies. J Postgrad Med 2016;62:51-2 |
Sir,
I went through with interest the article entitled "Incidence and factors associated with medication nonadherence in patients with mental illness: A cross-sectional study" published in the "Journal of Postgraduate Medicine" (2015; 16:251-6). [1]
The authors have conducted a cross-sectional study in the outpatient psychiatric department of a tertiary care private hospital over a period of 1 year and followed up the patients receiving at least one psychotropic medication for at least 1 month. The authors concluded that the overall incidence of medication nonadherence in patients with mental illness was 43%. I have concerns regarding the calculation of incidence for which reference to time is important. [2]
The authors have actually provided us with an estimate of the proportion of nonadherence among patients on psychotropic medication and not incidence. As incidence involves a reference to time; it is not expressed as a percentage (as done by the authors) but as person-time. [3] In contrast, the proportion in statistics refers to the fraction of the total that possesses a certain attribute such as nonadherence in case of this study.
Financial support and sponsorship
Nil.
Conflicts of interest
There are no conflicts of interest.
| :: References | |  |
| 1. | Lucca JM, Ramesh M, Parthasarathi G, Ram D. Incidence and factors associated with medication nonadherence in patients with mental illness: A cross-sectional study. J Postgrad Med 2015;61:251-6.  [ PUBMED]  |
| 2. | Szklo M, Nieto FJ. Measuring disease occurrence. In: Szklo M, Nieto FJ, editors. Epidemiology Beyond the Basics. 2 nd ed. Sudbury, MA: Jones and Bartlett Publishers, Inc; 2007. p. 47-76. |
| 3. | Raina SK. Incidence of malignancies in biopsy-proven inflammatory myopathy: Comment and erratum. Neurol India 2013;61:340. [ PUBMED] |
|
