Table 5.
A summary of survey frequency modeling to evaluate the incidence rate of reported arthritis as compared to the total number of dental amalgam filling surfaces per person in the NHANES database.
| Number of dental amalgam filling surfaces (percentile) | Total weighted persons with reported arthritisa | Total weighted-person-years | Incidence rate of persons with reported arthritis (per 10,000 weighted-person-years) |
|---|---|---|---|
| 0 (0-31) | 124 556 | 1 175 073 798 | 1.06 |
| 1 (32-40) | 49 120 | 428 117 858 | 1.15 |
| 2 (41-48) | 224 010 | 426 220 026 | 5.26 |
| 3 (49-56) | 353 700 | 414 411 402 | 8.53 |
| 4 (57-61) | 376 321 | 423 108 009 | 8.89 |
| 5 (62-66) | 139 568 | 239 487 089 | 5.83 |
| 6 (67-71) | 362 098 | 284 794 937 | 12.7 |
| > 6 (72-100) | 996 247 | 1 701 805 883 | 5.85 |
| > 13 (91-100) | 127 091 | 528 207 158 | 2.41 |
There was a significant increase in the incidence rate of reported arthritis (rate ratio = 8.6, P < .01) among those persons with 4 to 7 dental amalgam filling surfaces (9.27 per 10,000 weighted-person-years) as compared to those persons with 0 to 2 dental amalgam filling surfaces (1.08 per 10,000 weighted-person-years). There was a significant increase in the incidence rate of reported arthritis (rate ratio = 3.85, P < .05) among those persons with 4 to 7 dental amalgam filling surfaced (9.27 per 10,000 weighted-person-years) as compared to those persons with >13 dental amalgam filling surfaces (2.41 per 10,000 weighted-person-years).
The incidence rate of reported arthritis was derived from NHANES survey data among those persons with reported arthritis in the year of the NHANES survey collection. Those persons with reported arthritis at any time prior to the year of the NHANES survey collection were eliminated from the analyses.