Prevalence depends on incidence and duration
For a chronic condition, prevalence (the number of existing cases) is approximately incidence (the rate of new cases) multiplied by the average duration of the condition. If incidence stays constant, prevalence rises only when cases last longer, either because people live longer with the condition or because fewer are cured. In this registry, new cases stayed at about 150 a year from year 1 to year 5, while deaths among registered clients fell steadily from 120 to 41 a year. The registry grew from 600 to 960. With incidence unchanged and deaths falling, the growth in prevalence reflects clients living longer with hypertension.
Reading the trend
Each year the registry changes by new cases minus deaths, since no client moved away. In year 2, for example, 600 + 148 − 88 = 660; in year 5, 850 + 151 − 41 = 960. The fall in deaths began after maintenance medicines became free at the RHU at the start of year 2, which suggests that better access to treatment improved survival. Hypertension is not cured by treatment, so people who survive remain on the registry, lengthening the average duration and raising prevalence.
| Year | New cases | Deaths | Year-end registry |
|---|
| 1 | 150 | 120 | 600 |
| 2 | 148 | 88 | 660 |
| 3 | 152 | 62 | 750 |
| 4 | 149 | 49 | 850 |
| 5 | 151 | 41 | 960 |
Why the other explanations are wrong
Better case detection would show as a rising number of new diagnoses, but new cases stayed flat. An increased risk of developing hypertension would also appear as rising incidence, which did not happen. Program failure to control blood pressure would be expected to raise, not lower, deaths among registered clients. Watch out! A rising registry can look like a worsening problem, but a rising prevalence with stable incidence and falling deaths is a sign of better survival.
Exam takeaway
Prevalence ≈ incidence × duration: treatments that prolong life without curing raise prevalence. For planning, the growing registry means the RHU needs more medicines, follow-up slots, and monitoring capacity each year, even though the program is succeeding. When presenting the trend in the community diagnosis, the nurse should report incidence and deaths alongside prevalence so that decision-makers interpret the growth correctly.