Seasonal Variation in Diagnoses and Visits to Family Physicians

Article Figures & Data

Table 2.

Overall Percentage of Visits for Each Diagnosis and Percentage of Visits for Each Season

Family Physician Diagnosis	Subjects With Diagnosis No. (%)	Summer %	Fall %	Winter %	Spring %
* P <.001 (based on summer = June, July, August).
URI = upper respiratory tract infection; COPD = chronic obstructive pulmonary disease.
1. Hypertension*	1,462 (11.1)	12.6	12.2	9.9	10.0
2. URI*	1,450 (11.0)	5.7	11.5	15.1	10.8
3. Physical examination	1,125 (8.6)	9.1	8.0	8.2	9.0
4. Diabetes	696 (5.3)	5.9	6.0	4.4	4.9
5. Sinusitis*	625 (4.8)	3.3	4.4	5.8	5.4
6. Bronchitis*	614 (4.7)	2.5	4.4	6.3	5.2
7. Degenerative joint disease	529 (4.0)	4.2	4.4	3.7	3.8
8. Asthma*	485 (3.7)	2.6	3.3	4.7	3.8
9. Otitis*	425 (3.2)	1.8	2.5	4.5	3.8
10. Depression	380 (2.9)	3.3	2.9	2.7	2.8
11. Hypercholesterolemia	367 (2.8)	2.9	3.4	2.1	2.9
12. Rhinitis*	358 (2.7)	2.5	1.8	2.4	4.3
13. Back pain	357 (2.7)	3.2	2.5	2.1	3.2
14. Obesity*	265 (2.0)	2.9	1.8	1.5	2.0
15. Urinary tract infection	263 (2.0)	2.2	1.9	1.7	2.3
16. Pregnancy*	240 (1.8)	2.1	2.3	2.2	0.7
17. Headache (includes migraine)	224 (1.7)	1.5	2.1	1.8	1.4
18. Coronary artery disease*	201 (1.5)	2.1	1.8	1.6	0.7
19. COPD	193 (1.5)	1.6	1.6	1.6	1.2
20. Neck pain	190 (1.4)	1.8	1.7	1.0	1.3
21. Contact dermatitis	189 (1.4)	1.6	1.4	1.3	1.5
22. Anxiety	186 (1.4)	1.6	1.2	1.4	1.5
23. Hypothyroidism	168 (1.3)	1.2	1.4	1.2	1.2

Table 3.

Seasonal Variation of Diagnostic Clusters for 3 Different Seasonal Models for Summer

	Reallocation of Months Within Seasons,PValues
Diagnosis	Summer =June, July, Aug	Summer =July, Aug, Sept	Summer =May, June, July
Note: Original definition of summer = June, July, August.
Aug = August; URI = Upper respiratory tract infection; COPD = chronic obstructive pulmonary disease.
Sensitivity analysis on seasonality:
* Robust seasonality.
† Low seasonality. ‡ Moderate seasonality.
Hypertension*^†	<.001*	.012	.010
URI*	<.001*	<.001*	<.001*
Physical examination	.077	.028	.026
Diabetes	.013	.014	.124
Sinusitis*	<.001*	<.001*	<.001*
Bronchitis*	<.001*	<.001*	<.001*
Degenerative joint disease	.308	.744	.443
Asthma*	<.001*	<.001*	<.001*
Otitis*	<.001*	<.001*	<.001*
Depression	.422	.954	.119
Hypercholesterolemia^†	.015	<.001*	.224
Rhinitis^‡	<.001*^‡	<.001*^‡	.031^‡
Back pain^†	.015	.010	.001*
Obesity^‡	.001*^‡	<.001*^‡	.022^‡
Pregnancy^‡	<.001*^‡	.001*^‡	.033^‡
Urinary tract infection	.545	.728	.892
Headache	.329	.491	.133
COPD	.534	.840	.673
Neck pain^†	.032	<.001*	.013
Contact dermatitis	.741	.802	.896
Anxiety	.724	.270	.642
Hypothyroidism	.816	.398	.089
Coronary artery disease*	<.001*	<.001*	001*

Table 5.

Number of Times in 50 Samples With Diagnostic Cluster Visit Prevalence Estimates <1%, by Sampling Period

Diagnostic Cluster	Winter-Summer No. (%)	Spring-Fall No. (%)
Anxiety	5 (10)	4 (8)
Coronary artery disease	0 (0)	10 (20)
Chronic obstructive pulmonary disease	0 (0)	1 (2)
Contact dermatitis	5 (10)	0 (0)
Neck pain	5 (10)	2 (4)
Pregnancy	0 (0)	8 (16)
Hypothyroidism	4 (8)	7 (14)
Urinary tract infection	1 (2)	0 (0)
Headache	1 (2)	0 (0)
Diagnostic clusters with a visit prevalence <1%, total No.	21	32
Samples with at least 1 diagnosis with a visit prevalence <1%, total No.	20	24
Diagnostic clusters per sample with a visit prevalence <1%, mean No. (SD)	0.80 (SD 1.01)	1.12 (SD 1.26)

Supplemental Table and Figures

Table 6. Percentage of visits for each diagnostic cluster for winter-summer and spring-fall sampling strategies, compared with the full-year data set; Figure 1. Percentage of diagnoses; Figure 2. Percentage of diagnoses.

Files in this Data Supplement:

Supplemental data: Table 6 - PDF file, 1 page, 76 KB
Supplemental data: Figure 1 - PDF file, 1 page, 43 KB
Supplemental data: Figure 2 - PDF file, 1 page, 43 KB
The Article in Brief

Family doctors tend to treat the same types of illnesses and problems over time. Based on the season of the year, however, there is variation in the illnesses and problems that family doctors treat and in the ages of patients who visit them. In the winter, for example, family doctors treat more infectious conditions and have more visits by children than during other times of the year. An understanding of seasonal differences helps researchers study medical conditions that are frequently seen in primary care practice.