Table 1.
Estimated number of adults aged ⩾20 years reported with hepatitis C in NYC between 1 January 2000 and 31 December 2010 who were still in NYC in 2010
| Year of last report | Number of unique cases | Probability remained in NYC in 2010* | Estimated number remaining in NYC in 2010 |
|---|---|---|---|
| 2000 | 296† | 0·6527 | 193 |
| 2001 | 1853 | 0·6804 | 1261 |
| 2002 | 3268 | 0·7108 | 2323 |
| 2003 | 3895 | 0·7429 | 2894 |
| 2004 | 4666 | 0·7776 | 3628 |
| 2005 | 5599 | 0·8153 | 4565 |
| 2006 | 8498 | 0·8542 | 7259 |
| 2007 | 10842 | 0·8920 | 9671 |
| 2008 | 13718 | 0·9292 | 12747 |
| 2009 | 18668 | 0·9650 | 18015 |
| 2010 | 38479 | 1·0000‡ | 38479 |
| Total | 109782 | 101035 |
The probability of a case remaining in NYC in 2010 was derived by multiplying the annual probability of out-migrating for each year since the case was last reported to the surveillance system. Annual derived probabilities were as follows: 2009–2010 (0·965); 2008–2009 (0·9629); 2007–2008 (0·96); 2006–2007 (0·9576); 2005–2006 (0·9544); 2004–2005 (0·9538); 2003–2004 (0·9554); 2002–2003 (0·9568); 2001–2002 (0·9572); 2000–2001 (0·9593) [26].
First year of mandatory testing probably resulted in lower ascertainment. Most positive cases were retested and captured by the system in subsequent years.
The probability of living in NYC in 2010 if a person was reported to the database in 2010 was assumed to be 1.