From: Headache following head injury: a population-based longitudinal cohort study (HUNT)
 |  | N (%), head injury population | N (%), controls |
---|---|---|---|
HUNT2 | HUNT3 | ||
Decreased headache frequencya | 10 (12.5) | 939 (15.1) | |
> 14 days | 1–14 days | 2 (2.5) | 269 (4.3) |
7–14 days | <  7 days | 8 (10.0) | 670 (10.8) |
Stable headache frequencyb | 55 (68.8) | 4234 (68.0) | |
<  7 days | <  7 days | 46 (57.5) | 3833 (61.6) |
7–14 days | 7–14 days | 4 (5.0) | 257 (4.1) |
>  14 days | >  14 days | 5 (6.3) | 144 (2.3) |
Increased headache frequencyc | 12 (15.0) | 757 (12.2) | |
<  7 days | 7–30 days | 10 (12.5) | 633 (10.2) |
7–14 days | >  14 days | 2 (2.5) | 124 (2.0) |
Missing | 3 (3.8) | 293 (4.7) | |
Total | 80 (100.0) | 6223 (100.0) |